photobiology 0.9.20 (2018-04-02)
================================

* To improve clarity of user code, define wrappers for methods max(), min(),
range(), midpoint(), and spread() with names with wl_ prepended (e.g. wl_max()).
Rename method spread() to expanse() and deprecate use of spread().
In the case of wl_expanse() and expanse() the new names prevent a name clash
with tidyr::spread().
* Redefine all 'as.' class-coercion functions into generic methods, and add
specializations. Default behaviour remains unchanged.
* Add class-coercion methods to and from matrix (and transfer corresponding
functions from package 'photobiologyInOut').
* Add function relative_AM() to compute relative air mass from sun elevation.
* Add functions for calculation of saturated water vapour pressure from air
temperature and dew point from water vapour pressure.

photobiology 0.9.19 (2018-03-05)
================================

* Fix bug in sun_angles() that resulted in wrong azimuth values returned
in some circumstances. (Bug introduced in version 0.9.12 when the astronomy
code was overhauled in December 2016.)
* Fix bug in day_night() that resulted in a small time shift when a time was
passed instead of a date as an argument to parameter "date".
* Fix bug in irrad(), e_irrad() and q_irrad() methods for collections of
spectra which was resulting in arguments passed to parameter 'quantity' being
silently ignored.
* Add explicit support for optional parallel execution of apply functions, and
methods for collections of spectra. Apparently of no use under Windows 10, even
for large collections of spectra.
* Revise documentation.

photobiology 0.9.18 (2017-12-16)
================================

* Add calibration_spct class and its methods. Update all operators and maths.
functions to support this new class. Add corresponding test cases.
* Add calibration_mspct class and its methods.
* Add functions add_attr2tb(), when_measured2tb(), lon2tb(), lat2tb(),
geocode2tb() and what_measured2tb().
* Add a formal parameter "attr2tb" to all summary methods for collections of
spectra, used to automatically call add_attr2tb() to add attributes to their
output.
* Fix bug in calculation of solar time of day which could result in values > 24 h.
* Fix a bug in the extraction operator for spectral objects (could lead to
infinite recursion in rare occasions).
* Fix wrong value returned in some cases by is_tagged() due to a bug in the
definition of tag().
* Revise vignettes and documentation.
* Rebuild some of the example data objects adding metadata attributes.

photobiology 0.9.17 (2017-08-??)
================================

* Add function merge2object_spct() that constructs an object_spct from a
filter_spct and a reflector_spct, even if wavelengths differ.
Add methods T2Afr() and Afr2T() for converting transmittance to absorptance and
vice versa.
* Add method T2T() for converting between internal and total transmittance when
total reflectance is available.
* Implement maths operators and functions for absorptance (Afr).
* Add convenience functions for setting options for the evaluation of an
expression: using_photon(), using_energy(), using_Tfr(), using_Afr(), using_A().
* Add convenience functions for setting options for maths: photon_as_default(),
energy_as_default(), Tfr_as_default(), Afr_as_default(), A_as_default().
*Add convenience functions for setting options for diagnosis:
verbose_as_default(), strict_range_as_default().
* Add convenience functions for setting options for computation:
wb_trim_as_default(), use_cached_mult_as_default().
* Add unset_user_defaults() to clear all private options recognized by this
package.
* Implement new attribute "Afr.type" and methods setAfrType() and getAfrType().
Update copy_attributes() function and check_spct() methods to support
this new attribute. (subject to changes)
* Revise cps2Tfr() and cps2Rfr(): simplify validity tests and fix bug in
cps2Rfr().
* Add method join_mspct() to convert a collection of spectra into a data.frame
with multiple columns. This method is mainly intended for use when exporting
spectral data.
* Add spectral data for an Arabidopsis leaf as object_spct, filter_spct
reflector_spct objects, and two raw_mspct objects with the corresponding raw
detector counts from the spectrometer.

photobiology 0.9.16 (2017-06-25)
================================

Rename S3 method color() to color_of() to avoid a name clash with an S4 method.
A function color() calling method color_of() maintains backwards compatibility,
but use of color() is now deprecated.
Improve performance of sun_angles(). Convenience functions returning individual
angles, sun_azimuth(), sun_zenith_angle(), and sun_elevation(), also benefit.
Optimize performance of day_night(). Other functions returning individual times
for sun positions, sunrise_time(), noon_time(), sunset_time(), day_length(),
night_length(), also benefit.
** Performance optimization does not alter the returned values **
Revise the documentation corresponding to these functions and the "astronomy"
vignette to better describe how vectorization works for these functions.

photobiology 0.9.15 (2017-04-29)
================================

Laxen range test for cps in check_spct.cps_spct(), so as to avoid spurious
warnings and/or errors.
Make waveband() with no arguments valid.
Add na.omit() and na.exclude() methods for all spectral classes.
Functions na.pass() and na.fail() as defined in R work as expected for
spectra.

photobiology 0.9.14 (2017-03-21)
================================

Add methods isValidIntrDesc() and isValidInstrSettings().
Add methods trimIntrDesc() and trimInstrSettings().
Improve handling of metadata attributes when row-binding spectra with
rbindspct() so that all metadata can be restored by subset2mspct().
Revise print methods so that they are compatible with new format
of attributes in row-bound spectra.
Fix bugs in print method for summaries of spectra, and make output
match that of the print method for spectra (some metadata was not printed).
Fix bug in tag.mspct() method (bad default waveband resulted in no tagging).
Add example data for spectral reflectance.
Add test cases for all new code, and add additional tests cases for old code.
Add example data for white LED bulb as raw_spct, cps_spct and source_spct objects.
Improve documentation.

photobiology 0.9.13 (2016-12-18)
================================

Add functions sun_elevation() and sun_azimuth().
Add convenience functions trim2overlap() and extend2extremes().
Add print() methods for instr_desc and instr_settings classes.
Change threshold for automatic use of hinges when calculating summaries, so
that hinges are used by default in more cases.
Allow lists of length zero as argument to w.band, and treat them as equivalent
to NULL.
Make argument span = NULL behave in the same way in peak and valley related
summary functions as it has for some time in statistics in package 'ggspectra'.
Fix bug in the range check for counts per second which triggered warnings
too easily.
Change scaling of D2 and FEL spectra so that they are expressed in W m-2 nm-1.

photobiology 0.9.12 (2016-10-22)
================================

Enhancements:
Overhaul the astronomy related functions. Non-backward compatible changes
in their parameters. Code rewritten using Meeus' astronomical algorithms
resulting in better accuracy, much faster calculation of times for solar noon,
sunrise and sunset. In addition the new algorithm can be used for a broader
range of years, limited only by function julian() in R, which ignores leap
seconds.
Not fully backward compatible as returned values differ slightly from
those in older versions, as long as indexing has been done by name.
Add classes "solar_time" and "solar_date", constructor solar_time() and methods
is.solar_time(), is.solar_date(), as.solar_date(), format() and print(). Add
conversion function as_tod() returning 'time of day' from a datetime object.
sun_angles() and day_night() now return a data.frame instead of a list.
* The default for twilight argument is no longer "none", but instead "sunlight".
The string "none" is accepted, and is as before interpreted as the center of
the solar disk at the horizon, without correction for atmospheric diffraction,
which is a solar elevation of zero degrees. In contrast, "sunlight" is
interpreted as the upper rim of the solar disk at the horizon after approximate
correction for atmospheric diffraction, which is a solar elevation of -0.833
degrees, resulting in longer days.

Revise cbindspct() so that it stores the name of "idfactor" as an attribute and
set the retrieved value of the attribute as default in subset2mspct(). This
makes the conversion from a long form spectral object back into a collection of
spectra 'automatic' in many additional use cases.

Fix bugs:
normalize() now sets scaled attribute to FALSE.
fscale() now sets normalized attribute to FALSE.
Allow all summary calculations on re-scaled data, with a warning.
Fix bug in operator '*' between reflector.spct and source.spct, which triggered
an error.

photobiology 0.9.11 (2016-09-10)
================================

Fix bug in print.generic_spct().

photobiology 0.9.10 (not submitted to CRAN)
===========================================

Argument range.check = NA and range.check = NULL now trigger a message instead
of skipping the test altogether. Logical values retain earlier behaviour.
Fix bug in set functions for spectral classes: option "photobiology.strict.range"
was not obeyed.
Revise irrad(), e_irrad() and q_irrad() to accept as input scaled or
normalized source_spct objects as long as returned quantity is not "total" or
"mean", or its synonym "average". If the returned value will be in relative
units linear scaling or normalization will not invalidate the result, so earlier
restriction was unnecessarily strict.
Fix bug in cps2irrad().

photobiology 0.9.9 (2016-08-16)
===============================

Fix bug in rbindspct() affecting binding of object_spct objects.
Fix bug in sunrise_time() and sunset_time() with vector of dates input at
polar region latitudes.
Fix bug in e_ratio().
Convert User Guide from PDF (Rnw) to HTML (Rmd).
Fix some minor mistakes in documentation and build a documentation web site
with package 'staticdocs'.

photobiology 0.9.8 (2016-05-20)
===============================

Fix bug: insert_hinges() would fail for "raw_spct" and "cps_spct" objects.
Fix bug: leap year for year 2000.
Test, improve and document function sun_angles().
Clean code for handling of "range" arguments.
Make more consistent handling of "w.band" argument in spectral summary functions
such as irrad(): a numeric range is now a valid argument which is converted
on-the-fly into a waveband object.
Add "guard code" to summary functions triggering errors or warnings when the
spct object passed as argument contains data for multiple spectra in long form.
Fix bug in stepsize.generic_spct() and improve print() output for spct objects
containing data for multiple spectra (in long form) and their summaries.
Improve how print() handles large collections of spectra.

photobiology 0.9.7 (2016-04-??)
===============================

Edit to track changes to the behaviour of functions in package 'lubridate'
which triggered errors in several use cases of package 'photobiology'.

photobiology 0.9.6 (2016-04-02)
===============================

Optimize R code for performance: high-level functions faster than in version
0.9.4 (last version using Rcpp and C++).
Add support for "what.measured" attribute.
Allow multiple "countsXXXX" columns in "raw_spct" objects.
Allow multiple "cpsXXXX" columns in "cps_spct" objects.
Fix bug in getInstrSettings().
Allow small rounding and instrument errors to pass validity checks.
Fix bug in setRawSpct().
Implement clean(), normalize(), fscale() and fshift() methods for
"generic_spct", "raw_spct" and "cps_spct" objects.
[New functions: cps2irrad(), cps2Tfr() and cps2Rfr(). Preliminary versions.]
Constructors for _spct objects gain a ... formal argument which allows
addition of arbitrary columns to the objects created.
Reorganize documentation into fewer help files.
Fix bug leading to loss of special attributes. Add test cases.
Fix bug in "extract" operator [.object_spct.
Update for compatibility with dplyr (>= 0.4.3.9001).
Update tests for testthat (>= 0.11.0.9000).

photobiology 0.9.5 (2016-02-03)
===============================

Remove buggy C++ code and replace it with R code.
Performance cost: 20 to 30% slower in high-level functions.

photobiology 0.9.4 (2016-02-01)
===============================

Prepare for CRAN submission.
Rename check() -> check_spct() to avoid name clash with 'devtools'.
Fix bug in clean() methods for collections of spectra.

photobiology 0.9.3 (??)
==============================

Cosmetic changes.

photobiology 0.9.2 (2016-01-03)
===============================

Change tag.generic_spct() and wb2rect_spct() so that "wb.color" is also added
as a column to make it easier to define new ggplot2 stats based on them.
Make tagging compatible with raw_spct and cps_spct objects. Change
behaviour of w.band = NULL as argument to using a single waveband covering the
whole wavelength range of the spectral object, for consistency with other
methods. In addition change behaviour so that the same columns are added
independently of the value supplied as argument for "w.band", filling the
unused columns with NAs when w.band = NA.

photobiology 0.9.1 (2015-12-19)
===============================

Rename some "low level" functions and their formal parameters.

Rename the default methods for midpoint() and stepsize() as methods for
numeric and add a new default method that handles unsupported classes more
gracefully.

Revise color() method to work correctly in borderline cases. Returned value
is always of class character (character() or NA_character_ in some cases).
The default for the formal parameter 'type' is now consistently "CMF", instead
of in a few cases "both".

Revise interpolate_spct() (interpolate_wl.generic_spct()) to work correctly
in borderline cases and to handle gracefully numeric(). Also returned value
always has the same class and columns, irrespective of the values of
other arguments.

photobiology 0.9.0 (2015-12-16)
===============================

This version removes all two-way dependencies between this package and other
packages in the r4photobiology suite. This should make installation of the
source distribution a lot easier.

Fix minor bugs
--------------
All spectral object constructors return an object with length equal to zero when
called without arguments, or with argument "w.length" of length equal to zero.
Earlier behaviour was to return NA, which is not consistent with R's usual
expectations.

All constructors for collections of spectra return an object with length equal
to zero when called without arguments or with a list of length zero as first
argument "l". Earlier behaviour was to trigger an error, which is not
consistent with R's usual expectations.

Function trim_waveband() was not returning the values described in some
cases. Now the function really behaves as originally documented.

Several functions and methods have a 'range' argument, but semantics was not
identical in all. Now they all use the same semantics, similar to that used
in recent versions of ggplot2 for xlim() and ylim(). Setting a boundary to
NA means that the range extends to include all available data on a given
'end'. Whenever it makes sense a NULL range means that the range includes the
whole available range of wavelengths. The default value of 'range' for the
recently added method 'fshift()' has changed to be the first 10 nm at the
short wavelength end of the spectrum.

Removed functionality
---------------------
Function calc_filter_multipliers() has been deleted.

New data
--------
Add example data to make this package's documentation independent of other
packages in the suite.

Filters: clear.spct, opaque.spct, polyester.spct, yellow.gel.spct
Sensors: photodiode.spct, ccd.spct
Objects: black_body.spct, white_body.spct, clear_body.spct

New functionality
-----------------
Add method clip_wl() to more easily select data for a range of wavelengths.
Add method trim_wl() from trimming, and method interpolate_wl(). All three
methods are implemented for individual spectra and for collections of spectra.
Methods clip_wl() and trim_wl() have been also implemented for individual
waveband objects and for lists of waveband objects.

New functionality (only useful to package developers)
-----------------------------------------------------
Add new classes raw_spct and raw_mspct to store raw counts from spectrometers,
constructors raw_spct() and raw_mspct(), and corresponding setRawSpct() and
is.raw_spct() and as.raw_spct() functions.

Add methods getInstrDesc() and getInstrSettings(), and the corresponding
setInstrDesc() and setInstrSettings() to handle metadata about instrument and
instrument settings used to acquire the spectral data. These classes and
methods are building blocks to be used in the development of spectral-data
acquisition packages.

Why "0.9.x" started?
--------------------
Changes are backwards compatible but new classes were added and several existing
methods were implemented for them. Seven new methods were added and
implemented for all spectral classes and collections of spectra classes.
The new classes are being used for writing a new package intended to
replace package MayaCalc.

photobiology 0.8.11 (2015-11-20)
================================

Add method clean() for removing out-of-range spectral observations.
Add method fshift() for shifting the zero of the scale used to express
spectral data.
Add 'geocode' formal parameter to all functions related to sun angles.

Clean-up code and vignette. Update vignette.

photobiology 0.8.10
===================

Add support for "when.measured" and "where.measured" attributes in generic_spct
objects. Add methods setWhereMeasured(), getWhereMeasured(), setWhenMeasured()
and getWhenMeasured(). The first two methods are compatible with the output
of ggmap::geocode() and the last two with POSIXct objects as returned by
many functions in package lubridate, such as lubridate::now() and
lubridate::today(). All these methods are implemented for both generic_spct
and generic_mspct classes.

Implement methods to 'get' and 'set' attributes of summary objects of spectra.

Revise print() method for spectra to include the new attributes when available.
Rewrite summary() methods and print() method for spectral summaries. Now
output parallels the output of the print() method for spectra.

photobiology 0.8.9
==================

Small edit to msdply() to allow setting of column names. Update to _mspct summary
methods to use the names in the list of wavebands, if present, as column names
for the returned data frame.

photobiology 0.8.8
==================

Add function trim_mspct().
Implement normalize(), fscale(), peaks(), valleys(), tag() and untag() methods
for generic_mspct and derived classes.
Implement dim<- for generic_mspct and derived classes.
Fix bugs in msmsply() and mslply().
Implement sign(), round(), signif(), floor(), ceiling() methods for
generic_mspct and derived classes.
Implement log2(), cos(), sin(), tan(), acos(), asin(), acos(), cospi(), sinpi()
and tanpi() methods for generic_mspct and derived classes.

Make internal changes needed for an update to photobiologyInOut.
Add option "photobiolgy.strict.range" to allow changing the default behaviour
for out-of-range values. (Used internally to avoid redundant checks and
repeated warning messages.)

Update package Title in docs.
Update User Guide, tables and their formatting.

photobiology 0.8.7
==================

Many bug fixes, mostly minor.
Rename f_mspct() to msdply() to respect name conventions in common use.
Add mslply() and msaply().
Implement operators %/% and %%, and function abs() for spectra.
Update documentation. Revise titles of help files.

photobiology 0.8.6
==================

Bug fixes related to imports from other packages.
Rename mutate_mspct() to msmsply() to respect name conventions in common use.
Add constructor chroma_spct().
Update documentation.

photobiology 0.8.5
==================

Implement extract and replacement methods for collections of spectra.
(Please, let me know if you encounter any errors with these methods, as
some testthat tests give infinite recursion errors that I cannot reproduce
outside testthat.)

Implement combine method c() for collections of spectra.

Add function convolve_each().

Add helper function shared_member_class().

photobiology 0.8.4
==================

Expand sun.spct and sun.daily.spct down to 280 nm with zeros.

Add methods for construction of collections of spectra from
data frames with different spectra in side-by-side columns
('untidy' or wide data):
split2source_mspct(), split2response_mscpt(),
split2filter_mspct(), split2reflector_mspct(), and
split2cps_mspsct()

Add method for construction of collections of spectra from
data frames with spectral data for different spectra in a
single column ('tidy' or long data), and spectral objects
containing several spectra, such as those returned by
function rbindspct():
subset2mspct()

Add print() method for collections of spectra.

Fix minor bug in trim_spct() which was inserting hinges on
head and/or tail expansion even if use.hinges was set to
FALSE.

Fix bug in rare borderline cases where NA was being returned
instead of empty spectral objects (objects with zero rows).

photobiology 0.8.3
==================

Improve handling of multiple.wl > 1 to avoid spurious warnings.
Fix minor bugs in spread().

photobiology 0.8.2
==================

Fix bugs in trim_spct() and reduce trimming rounding protection
in operators for spectra.

photobiology 0.8.1
==================

tag() and untag() by default use copy semantics.
Spectral objects with zero rows are handled cleanly.
$<- defined for spectra.
Fix bugs.

photobiology 0.8.0 (2015-07-29)
===============================

No longer use data.table as a base class for spectral objects.
** Given the size of spectral data the advantages were too
limited compared to the complications introduced. **

Extract and replacement methods "[" and "[<-" and the subset()
function should now work as expected when applied to spectral
objects!  Subscripting of spectra can be used without
any restrictions.

Argument passing and assignment semantics follows normal
R semantics of passing of making, `lazily', a copy, except in
a few exceptions.

Improved accuracy of returned values (from the earlier level
of approximately 4 significant digits to close to 7 or 8
significant digits when using hinges) and improved
consistency of returned values between functions and
operators.

New print method for spectral objects.

Several rather minor bugs and inconsistencies fixed,
specially in operators.

Several dependencies and suggests removed. No imports are
now visible to users, which should avoid clashes.

** code is not yet optimized for performance **

** Hopefully not many bugs have been introduced **

photobiology 0.7.1
==================

Fix bug in new code added in 0.7.0.
Update rbinspct() to work well with _mspct objects as argument.
Add is. and as. functions for all _mspct classes.
Add function msmsply() and improve code of function f_mspct()
using package plyr.
Implement e2q() and q2e() methods for objects of classes
source_mspct and response_mspct.
Implement T2A() and A2T() methods for objects of class
filter_mspct.
Implement min(), max(), range(), spread(), midpoint() and
stepsize() for objects of class generic_mspct and derived classes.
Implement dim() for objects of class generic_mspct and derived
classes, which also makes available functions ncol() and nrow()
for objects of these classes.
Add function rmDerivedMspct().
Change returned value of rmDerivedSpct() into a character vector
containing the removed class attributes.
Update and reorganize User Guide.
Add tests for new code.

photobiology 0.7.0 (2015-07-03)
===============================

Make ratio functions into methods, and add 'wb.trim' as a parameter.
Remove 'pc.out' parameter from methods that had it.

Add _mspct classes and summary methods for collections of spectral
objects (the 'm' in _mspct comes from 'multi'. The idea for these new
classes came from a question from Susan Holmes after my talk
at UseR!2015 in Aalborg. She asked whether my package could handle
hyperspectral image data. I answer not, but that this feature could
be easily added. As with the rest of the package I have now a first
design that avoids as much as possible making assumptions about the
data, and allows as much extensibility as possible.

Add attribute 'spct.version' to all spectral objects, and function
getObjectVersion() to query it.

Changed upgrade() method into upgrade_spct() function, and now it
also adds the attribute 'spct.version' during object update.

Add function normalized_diff_ind() usable for calculation of indexes
similar to NDVI (normalized difference vegetation index) for
reflectance and any other spectral summary quantity and two
waveband objects. This was inspired by a poster in Aalborg about
package hsdar for analysis of hyperspectral images.

Revise User Guide and Upgrade Guide.

photobiology 0.6.8
==================

Functions sunrise_time(), noon_time(), sunset_time(), day_length(),
night_length() and day_night() gain formal parameter 'unit.out',
but its default value preserves earlier behaviour.

New generic functions peaks() and valleys().

subset() methods for spectral objects gain a new parameter 'idx'.
During sub-setting, tags are removed from the returned spectrum.

Functions is.photon_based(), is.energy_based(), is.absorbance_based()
and is.transmittance_based() have been renamed by replacing the dot
with an underscore for consistency with other functions not
test for object class.

Fixed bug in trim_waveband().

photobiology 0.6.7
==================

Fix bug in functions day_length() and night_length() added in 0.6.6.
The bug was triggering an error in calculations for polar regions.
(Test cases added.)

photobiology 0.6.6
==================

Package 'lubridate' is no longer imported, so to use functions from
this package, users must explicitly load it.

A user reported that day_night() was not vectorized as stated in the
documentation. This bug has been fixed, and now day_night() and the
new functions noon_time(), sunrise_time(), sunset_time(),
day_length() and night_length() are all vectorized for the 'date'
parameter. The default 'tz' for all the functions in now "UTC", to match
the default time zone used to obtain the default for 'date'. The 't'
argument of day_night() has been renamed 'date' for clarity.

These changes, may break old user code! (but needed changes will be
minor).

photobiology 0.6.5
==================

Add support for "twilight" definition as angle in degrees in function
day_night(), and different angles for sunrise and sunset.

Fix bug in calc_multipliers() that resulted in NAs in cases where
normalization wavelengths fell outside the range of a waveband object
but could be anyway computed without errors because the BSWF was
defined over a wider range of wavelengths than the waveband itself.

Updated dependency versions.

photobiology 0.6.4
==================

Add support for lubridate::duration:
Parameter "time.unit" in methods and functions related for source_spct and
response_spect objects accepts durations.

New function convertTimeUnit()
can be used to modify the time.unit attribute, re-expressing the spectral
data using the new "time.unit".

Old function setTimeUnit() issues a warning when it is used to override an
already set "time.unit" attribute.

Methods irrad(), e_irrad() and q_irrad(), and response(), e_response() and
q_response() gain parameter 'time.unit' which can be used to obtain their
result expressed on a different time-unit basis.

New methods fluence(), e_fluence() and q_fluence().

Fixed bug in absorptance.filter_spct().

Replaced "." by "_" in the names of the classes returned by summary() methods
for spectra.

photobiology 0.6.3
==================

Fixed long-standing bug in twilight calculation in function day_night().
irrad(), e_irrad(), and q_irrad() modified so that NAs in the spectral data outside
the range of waveband(s) do not cause the result to be an NA.

Documentation and User Guide updated.

photobiology 0.6.2
==================

Added new class cps_spct for uncalibrated spectral data in counts per second.
These are not raw instrument counts, but data linerized and re-expressed per unit
time in seconds. Maths operators and functions are supported.

Added new accepted value for attribute time.unit: "exposure", meaning the
total exposure time, in which case instead of spectral irradiances, the
objects store spectral fluence or spectral dose.

Added data for CIE standard A illuminant.

Changed package data files to contain each only one R object.

Updated User Guide adding summary tables for spectral objects and their
variables and attributes.

photobiology 0.6.1
===================

Added User Guide vignette with upgrade instructions.

Added new functions is.old_spct() and upgrade_spectra()

photobiology 0.6.0
===================

I am reading the new book "R Packages", authored by Hadley Wickham, and I have
found several things to improve in the package, especially with naming conventions
and documentation. I have earlier followed "common practice" or tried to
make names consistent with data.table. As the package has not yet been
publicly released, I am taking this last chance I have of getting the
naming conventions improved.

Major backwards-incompatible changes to function names to avoid method dispatch problems.
All function and class names use underscores. Only S3 methods have dots, and only between
method name and class names. Although many names have changed, they should be still
easily recognizable to current users.

Added test for non-unique wavelength values during spectral object construction,
and added a new formal argument to check() and set...() functions to allow
setting the maximum number of copies allowed. Current version only triggers
a warning.

Generic function Rescale() has been replaced by methods for the generic function scale()
defined in R base, and is_rescaled() has been renamed is_scaled().

IMPORTANT: because the .spct classes have been renamed, objects created with
earlier versions of the package are not recognized. They need to be "upgraded"
with function upgrade().

Full overhaul of the documentation, using features of latest version of package roxygen2.
Documentation for related functions is now on the same file, and most pages are cross-
referenced.

photobiology 0.5.19
===================

Added specialized subset() methods for spectral objects as subset.data.table drops attributes.
The new methods are wrappers that copy the attributes used by this package after the subset()
operation is done by subscripting, including comment, but still drop any attributes added
by users.

Edited check.generic.spct() to generate a warning instead of an error for spectra
of length zero, as can be returned by subset when the 'subset' condition is FALSE for
all rows.

photobiology 0.5.18
===================

Fixed bug in rbindspct().

photobiology 0.5.17-1
=====================

Updated version requirements for all dependencies.

photobiology 0.5.17
===================

New options "photobiology.use.hinges" (NULL, TRUE, FALSE) with default NULL and
"photobiology.auto.hinges.limit" (wavelength step in nm) with new default 0.5 nm.
Default behaviour is changed both for a bug in irrad() functions where the
limit was 1.1 nm instead of 0.7 nm and as a result of changing to a smaller
default value. Existing and new options "photobiology.waveband.trim",
"photobiology.use.cached.mult" are now used throughout.

Bug fix: in version 0.5.? the behaviour of the product of a BSWF and a source
spectrum was changed to return a response spectrum. This was not consistent with
the idea that a BSWF is used for quantifying radiation rather predicting a
biological response. The result should remain as radiation and continue to
be expressed in energy or photon based units. This has been fixed. Starting
from the current version, if the waveband is used with the '*' operator is
a BSWF (tested with function is_effective()) the resulting spectrum is tagged
as being "effective". The irrad() methods for source.spct have been updated to
'recognize' effective spectral irradiance when supplied as input.

rbindspct() modified so that if at least one of the spectra in the list is of
effective irradiance, but not all spectra have been calculated with the same
BSWF and normalization, a factor named BSWF is added with the BSWFs retrieved
from the spectra used as levels. The optional factor selected through parameter
idfactor has now its levels always reflecting the order of the spectra in the
input list, even when using a named input list of spectra. Several rather minor
bugs were fixed, including improved handling of comments and attributes.

summary() methods for spectra have been updated to report the BSWF that have
been used if source spectra contain effective spectral irradiances.

Long-standing unsolved problem partly fixed: interpolate_spct() now in most
cases applies smoothing to the spectrum before attempting interpolation if
the vector of output wavelengths has length > 1, but is sparser than then
original spectral data.

A few inconsistencies in the formal parameters among similar functions were fixed
by adding the missing parameters. Also some problems in the documentation
for a few functions were fixed.

User guide updated.

photobiology 0.5.16
===================

Fixed handling of attributes in insert_spct_hinges() and added support for
object.spct to this function. Also fixed small bugs here and there in the
handling of attributes, to make behaviour more consistent. Added tests
to avoid already set attributes to be overwritten by defaults when using
set...() and as....() functions on existing .spct objects.

Added warnings to default methods of generic functions to easy the diagnostic
of problems.

photobiology 0.5.15
===================

New functions normalize() and rescale() for spectra. Both functions set object
attributes to flag the spectra that have been modified, and no longer are
expressed in absolute units. In addition, tests were added
to summary functions to disallow use of rescaled or normalized spectral data as
input, with the exception of function integrate_spct().

Function rbindspct() was revised to issue a warning when only some of the spectral
objects are rescaled or normalized.

Changes in the code for handling 'time.unit', 'Tfr.type' and 'Rfr.type' attributes.
Added new functions getTimeUnit(), getTfrType() and getRfrType().

New test cases were added.

photobiology 0.5.14
===================

New class and methods added: object.spct, with the corresponding as.object.spct(),
is.object.spct(), setObjetcSpct(), and check.object.spct() functions. Also
functions reflectance() and transmittance() are implemented. New function
absorptance() is implemented only for object.spct objects. Objects of this
class can be used to store corresponding spectral transmittance and spectral
reflectance values. No operators are defined for this class as they would be
ambiguous. The class attribute needs to be changed to either filter.spct or
reflector.spct before using operators, however, no data is lost in the process,
or written except for the class attribute, so the class can be changed back to
object.spct if needed.

New function added: merge.generic.spct() is a wrapper on merge.data.table()
that sets the correct class to the returned merged spectra, preserves attributes
used with .spct objects and by default merges by w.length.

photobiology 0.5.13
===================

New function smooth_spct() for spectra added. Based on the smoothing code in
package MayaCalc and optionally behaving as a wrapper to other smoothers
available in R. Implemented for source.spct, filter.spct, reflector.spct
and response.spct objects. Its interface may change. Now package caTools is
needed.

Operations between .spct objects and numeric vectors, possibly of length one,
now preserve other variables (e.g.\ ID factors) contained in the spectral objects.

Fixed bug in reflectance() function.

photobiology 0.5.12
===================

Bad input error reporting improved for off-range Tfr and Rfr values in check().
Warning given by T2A() when Tfr = 0 result in A = Inf.
Added na.rm = TRUE when min() and max() are called on spectral data.

The formal arguments added to function rbindspct() in version 0.5.7 have been
changed to more closely follow the development version 1.9.5 of package
data.table. This will break user code that uses the previous
syntax as added a few weeks ago to this package.

Fixed bug in handling of 'quantity' arguments "contribution.pc" and "relative.pc"
in function absorbance() which was affecting plot annotations.

photobiology 0.5.11
===================

Changed code of irrad() and set___Spct() functions to be able to handle locked data.table
objects such as .SD when using by within [ ] on spct objects. irrad() copies the spectrum
only if needed, and the sorting key is set to "w.length" only if not already set to this
same value.

photobiology 0.5.10
===================

Added automatic testing based on package testthat.

Test cases for operators and math functions.
Test cases for constructors of spectral objects.

photobiology 0.5.9
===================

Updated operators' code so that unary '-' and unary '+' now work for spectra.

Rewrote the code for math functions, removing redundancy, and adding support for
chroma.spct objects.

Fixed a major bug in binary operators code for non-transitive operations, triggered
when the first operand is numeric.

Added a table to the User Guide summarizing the valid and invalid binary operations, and
a second table listing unary operators and math functions.

Edited the constructors of spct objects so that they recognize additional variable names
for the input data, and rename them.

Added warning messages informing of forbidden operations between dissimilar
spectral objects and between spectral objects and wavebands are attempted.

photobiology 0.5.8
===================

Bug in q2e.response.spct() fixed.

photobiology 0.5.7
===================

rbindspct() now will add, if requested, a factor 'spct.idx' to the returned spct object,
with a different level for each spectrum in the input list.
rbindspct() now works as expected even if spectra of the same class contain data stored
using different types of quantities, e.g. energy or photon based, or transmittance vs.
absorbance.
User Guide text was edited. Code formatting in chunks improved.

photobiology 0.5.6
===================

Added function clear_photobio.cache() and renamed the cache itself to "protect"" it from accidental
deletion by making it invisible.
Optimized colour calculations for improved speed and debugged the changes.
Revised User Guide.
Fixed bug that was causing response() not to be exported.
Fixed bug in operations between spectra and wavebands and added also a small safety margin
to protect from rounding errors.
A few minor bugs also fixed.
Fixed an important bug causing error in plot(sun.spct * CIE()) (a difficult one to track).

photobiology 0.5.5
===================

Changed the default for the trimming of wavebands to TRUE, and added a global option so that
the default can be changed globally by setting the option: e.g. using
options(photobiology.waveband.trim = FALSE)

Also added waveband trimming handling to function tag().

photobiology 0.5.4
===================

Fixed bug in split_bands() function. Handling of names has changed to some extent, and handling
of list objects supplied as x argument is now done by recursion, adding some additional flexibility.

The User Guide was updated to include examples of the use of split_bands().

photobiology 0.5.3
===================

Added function is_tagged() to easily test if an spectrum has been tagged for plotting.
Added function untag() to delete tag data from spectra.

photobiology 0.5.2
===================

Fixed bug in operators that caused the 'time.unit' attribute not to propagate to returned values.
Fixed bug in operations between wavebands and spectra which resulted in the returned
spectrum being expanded to the range of the waveband even if the operand spectrum did not overlap
this range.

The option "photobiology.base.unit" has been renamed "photobiology.radiation.unit", for consistency
with package photobiologygg and for clarity.

photobiology 0.5.1
===================

Added missing response.spct() function.
Fixed two bugs in new_waveband: 1) wb.label was not set when wb.name was auto-generated!
2) Both hinges were on the outside of the waveband, giving trouble with wavebands sharing
their limits.

Added new function trim_waveband().
Edited irrad(), response(), transmittance(), absorbance(), reflectance(), ratio() functions
for spectra to use this function internally, and gaining the wb.trim parameter, which defaults
to FALSE. Fixed small numeric errors in the creation of the waveband for the whole spectrum.

photobiology 0.5.0
===================

The default data in spectral objects has changed in the present and the previous versions. This is
to avoid, when possible, conversions when creating spectral objects. Instead, the input is
checked in the functions accepting spectral objects as input. However, values are never stored
as percentages, only as fractions, as this does not affect later computations, and when a percent
is needed the result of the computation is just multiplied by 100.

I added absorbance related functions, similar to the transmittance and reflectance ones: absorbance_spct()
and absorbance(). All these functions, as well as those for irradiances and ratios, and responses
now return values with the "radiation.unit" attribute set. In addition several edits were done to simplify the code when possible. Irradiance, response, transmittance, reflectance and absorbance functions have gained
a new parameter 'quantity', that can take one value out of "total", "contribution" (to total as a fraction), "percent" (contribution as percent), or "average" (the total divided by the 'spread' or width of the waveband in nm). New function response().

Options for operators and functions added:
options(photobiology.base.unit = "energy")
options(photobiology.base.unit = "photon")
These options determine whether operations are carried using energy based or a photon based quantities.
This affects operations involving source.spct and response.spct objects when using operators,
and the defaults for "unit.out" for functions accepting spectral objects as arguments.

options(photobiology.filter.qty = "transmittance")
options(photobiology.filter.qty = "absorbance")
determine whether operations are carried using transmittance or absorbance quantities
(this affects operations involving filter.spct objects).

The defaults remain the same as in earlier versions, except for irrad() which instead of having
no default for "unit.out" now uses the one set by the option, if the option is set.
Options can be unset with NULL.
options(photobiology.base.unit = NULL)
options(photobiology.filter.qty = NULL)

Moved functions find_peaks(), get_peaks() and get_valleys() from photobiologygg to this package.

User Guide thoroughly updated to reflect currently available functionality, including
the options described above.

Fixed bug in trim_spct() which led to wrongly copied attribute for filter.spct objects.

photobiology 0.4.10
===================

The code for the operators has been rewritten almost from scratch. The code for the special
functions has been edited. In addition to cleaner and more compact code, now the order of
the operators does no longer affect the dispatch of the operators for spectral objects.
There are some changes in which combinations of arguments are accepted. The checking is
now more strict with respect to what may make sense from the point of view of the physics
behind the calculations. Failed checks return NA.

All calls to invisible(), except in the \texttt{set\_\_\_Spct} functions, have been replaced
with return() as the lack of visible output was confusing. It is now documented in the
User Guide how to use options() to control the length of the print output.

photobiology 0.4.9
===================

Generic functions e_response() and q_response() added, and debugged.
Changed check() for source.spct and response.spct so that it does not add "energy" or "photon" based spectral data
on building objects, as this adds unneeded computation and complicates the logic by changing the
data on copy operations (which is surprising and can lead to difficult-to-trace bugs.)
This change can be NOT BACKWARDS compatible in some cases of user code, but should be fine for
other functions defined in the photobiology packages, as they have been edited to maintain the
same visible behaviour.

Fixed a spurious warning by trim_spct() due to minute differences in wavelengths.

photobiology 0.4.8
===================

Tweaked handling of w.high by new_waveband().
Fixed bug in function waveband() which caused it not to properly create weighted wavebands.
Improved handling of names by split_wavebands() and improved the documentation.

photobiology 0.4.7
===================

Added function is_waveband().

photobiology 0.4.6
===================

Fixed various small bugs. Removed rbindlist(), for spectra rbindspct() should be used instead.

photobiology 0.4.5
===================

Added waveband() constructor function.
Fixed bug in reflectance_spct() and reflectance() functions.
Fixed bug in class_spct().
Revised the user guide to reflect all changes to the code done in the last few versions.

photobiology 0.4.4
===================

Added the remaining as.xxxx.spct() functions.
Added object creation functions source.spct(), filter.spct() and reflector.spct().
Cleaned code to avoid some warnings.

photobiology 0.4.3
===================

Fixed bug in functions transmittance_spct() and reflectance_spct(), and added aliases transmittance() and reflectance().

photobiology 0.4.2
===================

New function rmDerivedSpct() now used internally for setting xxx.spct classes consistently by removing derived class attributes when class is set to parent class.

New as.generic.spct() and as.private.spct() functions for spct objects to easy use of operators.

Bug in default arguments to rbindspct() fixed.

photobiology 0.4.01
===================

Fixed a troublesome bug caused by a couple of missing exports. MayaCalc was broken because of this.

Moved functions D2_spectrum() and FEL_spectrum() to this package from photobiologyLamps

photobiology 0.4.00
===================

Started new development branch.
Added is.xxx.spct() functions for all classes defined and is_any_spct() and class_spct() functions to query class of spectral objects.

photobiology 0.3.16
===================

Edited wb2xx functions. Added other required variables and set their values to zero, so that the generic.spct objects returned by the waveband to spectra functions can be safely converted to any of the specialized spct spectral objects. This makes then labelling of all types of spectral plots equally easy.

photobiology 0.3.15
===================

Never released, changes reversed.

photobiology 0.3.14
===================

The required component of response.spct objects was renamed from 'response' to 's.e.response'. 'response' is also accepted and renamed into 's.e.response'. If 's.q.response' is present it is accepted and maintained. New methods e2q() and q2e() for response.spct class.

photobiology 0.3.13
===================

Replaced several 'return' statements with 'invisible'.
Replaced all remaining data.frame() calls with data.table().

photobiology 0.3.12
===================

Changed the name of two of the variables added by wb2rect_spct() to more meaningful ones.

photobiology 0.3.11
===================

Added setGenericSpct() as a synonym for setGenSpct() to keep naming consistent. Added functions wb2tagged_spct() and wb2rect_spct() for creating a tagged generic.spct objects suitable from a list of wavebands.

photobiology 0.3.10
===================

Updated vignette to use new package photobiologyWavebands.
Added a generic function tag() and methods for generic.spct and source.spct objects. tag() can be used to 'tag' the rows based on a list of wavebands, or simply with rgb color equivalents. A color() method for source.spct() was added, which returns the overall colour of the spectrum as a whole. Fixed a 'bug' in tag() that increased execution speed a lot. Added CIE2008 human luminous efficiency function data. Added functions irrad(), q_irrad() and e_irrad() as synonyms for irrad_spct(), q_irrad_spct() and e_irrad_spct(). Added functions irrad(), q_ratio(), e_ratio(), eq_ratio(), and qe_ratio() as synonyms for q_ratio_spct(), e_ratio_spct(), eq_ratio_spct() and qe_ratio_spct(). eq_ratio_spct() is also a new function. Added function split_bands() for creating lists of unweighted wavebands. Several bug fixes, and new function put_hinges(). Added function rbindspct() and redefined rbindlist() (hiding data.table::rbindlist() by exporting photobiology::rbindlist() instead.) Also some changes to color() with new methods for numeric and lists.

photobiology 0.3.9
===================

Added summary() and corresponding print() methods for spectral objects, and stepsize() default and "generic.spct" methods. Changed SetSourceSpct() to accept a "time.unit" argument, which is used to set an attribute in "source.spct" objects (defaults to "second" making it transparently backwards compatible).

Performance tests show that with default settings the irradiance functions for "source.spct" objects execute significantly faster than the vector based ones. Operators for spectra are at the moment relatively very slow.

photobiology 0.3.8
===================

Now chromaticity and colour matching function data are as chroma.spct objects. This required also edits to many of the colour related functions. Added CMF for honeybees and example daily solar spectral data. Edited irrad_spct() so that results always include waveband names.

photobiology 0.3.7
===================

Added new class response.spct and revised the operators' definitions.

photobiology 0.3.6
===================

The set...Spct() functions until 0.3.5 had different semantics than setDT in data.table. This has now been fixed.
Data for CIE D65 illuminant has been added. The imports and re-exports from data.table now include additional functions including some new to data.table 1.9.3.
Added new class chroma.spct for storing x y z chromaticy data and the corresponding functions setChromaSpct and operators * and /.

photobiology 0.3.5
===================

Fixed "bug"" in trim_spct(), which was returning data.table objects instead of objects of the same type as supplied as argument. A bug in version 1.9.2 of data.table was behind some other problems, so added requirement for data.table 1.9.3+ to DESCRIPTION.

photobiology 0.3.4
===================

Added a class for reflectance spectra and updated operator definitions. Added function setReflectorSpct().
New functions interpolate_spct(), reflectance_spct(), transmittance_spct(), q_ratio_spct(), e_ratio_spct(), qe_ratio_spct(), rgb_spct() and check(), check.generic.spct(), check.filter.spct(), check.reflector.spct(), and check.source.spct(). Operator *.generic.spct now accepts wavebands as second argument.
Debugged min(), max(), range(), midpoint(), spread(), labels() for spectra.
Updated setGenericSpct(), setFilterSpct() and setSourceSpct() to use check() to check and fix if possible missing variable, or add the missing variables as a vector of NAs.

Updated the vignette with examples of the use of spct objects and the functions and operators defined for them.
Modified packages so as to consistently use .spct as the name tag of all objects representing spectra. Recently .dt was used and earlier, .data, that is still a fall-back in the current version.

TODO: make sure all spct functions and operators work correctly when the argument spct objects are incomplete.

photobiology 0.3.3
===================

New functions insert_spct_hinges(), trim_spct(), integrate_spct(), average_spct(), irrad_spct(), e_irrad_spct(), q_irrad_scpt(), transmittance_spct(), reflectance_spct(), ... , is_effective.waveband(),
Small edits to new_waveband()
Example solar spectrum  data now available as "source.spct" objects and as "data.table" and "data.frame" so as not to break any old code.

photobiology 0.3.2
===================

Function day_night had bugs, now fixed.

photobiology 0.3.1
===================

Added functions sun_angles and day_night.

photobiology 0.3.0
===================
************ MAJOR UPDATE ****************
There are some backward incompatibilities

Saved wavebands will give an error, but any
code used to create them should still work
unchanged.

If you used the parameter use.cpp.code in
your code, you will just need to delete
the corresponding arguments. C++ code is
always used.

I hope I haven't broken anything else but
I have made quite major internal changes.

At the moment the code is a bit slower than
before. I will most likely be able to cure
this at a later stage.
******************************************

The package now depends on data.table which is now imported. As MayaCalc already returns data.table objects, hopefully this will help optimize performance and memory use. Users should be aware that data.tables are copied by reference, and a true copy is needed, function copy should be used.

I am making the code more object (S3) oriented. Three new classes are exported "filter.spct", "source.spct", and "generic.spct", and three new functions were added to set the class of objects to these classes. If the object is not already a data.table, it is setDT. This allows me to create a more user-friendly interface by overloading operators. Now the four basic operations work on spectra, and one can also use these same operations and ^between a spectrum a numerical vector of length one or longer. Many maths functions and some summary functions have specialized versions for spectra. This is my attempt to make calculations intuitive, but do not expect them to be fast.

Added generic functions A2T and T2A for converting absorbance to transmittance and back. The generic function takes a numerical argument, and there are special versions for spectra. When the argument is a "filter.spc" object they return a copy of the original object with the calculated quantity added. If the requested output already exists, it is NOT recalculated, just a copy of the argument is returned, if the input data is missing, the corresponding output is set to NA.

Added a label field to waveband object to store an optional label for plotting, which by default is set equal to the name of the waveband. labels.waveband was changed to return in field label this label instead of the name, and the name is returned in the field name. Also added a new function normalization.waveband that returns the normalization wavelength.

calc_filter_multipliers now accepts both a filter name as a character string or an object of class "filter.spct" as argument to parameter filter (which was renamed from filter.name). In addition the function acquired a pc.in logical parameter, an the pc parameter was renamed pc.out. This allows any combination of input and output as percentages or fractions.

photobiology 0.2.25
===================

Modified calc_filter_multipliers to work with photobiologyFilters 0.1.8 and later
Both calc_filter_multipliers and calc_source_multipliers now find by name both objects with ending .dt and .data. If both exist .dt is used.

photobiology 0.2.24
===================

Added functions oper_spectra, prod_spectra, div_spectra, and subt_spectra, and redefined sum_spectra based on oper_spectra. Behaviour of sum_spectra has not changed.

photobiology 0.2.23
===================

Removed center_wl center_wl.generic and center_wl.waveband
Added spread spread.generic and spread.waveband
Added midpoint midpoint.generic and midpoint.waveband

photobiology 0.2.22
===================

Moved from photobiologyLamps and renamed function calc_lamp_output() to calc_source_output().
Moved from photobiologyLamps calc_filter_multipliers().
Added two examples of how to draw Maxwell's triangles.

photobiology 0.2.21
===================

Fixed a bug in s.e.irrad2rgb() caused by not explicitly handling the case when the wavelength range was completely outside outside the range of the the CMF or CC data. In other words the function crashed when the colour of invisible radiation was requested. Now "black" is returned in this case.

photobiology 0.2.20
===================

New function w_length_range2rgb(), which takes a range of wavelengths, and returns the equivalent RGB colour assuming equal spectral (energy) irradiance at all wave lengths within the range.
Modified the calculation of color for wavebands, using this new function.

photobiology 0.2.19
===================

Added waveband versions of generic functions, min(), max(), range() and labels().
Updated trim_tails() so that it can also expand a spectrum.
New functions:
w_length2rgb() to calculate RGB colour definitions for monochromatic light.
s.e.irrad2rgb() to calculate RGB colour definition from spectral irradiance data or reflectance data.
Data on x, y, z coordinates for CIE chromaticity coordinates and colour matching functions added.

photobiology 0.2.18
===================

Fixed a bug in split_irradiance() and improved handling of cut point values outside the data range, unsorted cut-points, and redundant cut-points. For 'good' data there are no changes in output, except in the case when three cut points were supplied, as the third one was being ignored. The handling of out-of-range cut points has been changed so that the endpoints are moved to the extreme wavelengths of the data.

photobiology 0.2.17
===================

The cache is now created in the "emptyenv". This solves a long-standing error message during installation.

photobiology 0.2.16
===================
Changed irradiance() so that it optionally accepts a list of wave_bands and returns a vector or irradiances. The returned values have a names attribute set to the names of the elements in the wave_band list. If the names are missing, it returns the "name"s stored in the wave_band objects.

wave_band objects are now S3 objects with class "waveband", a print.waveband() function was added, which is called whenever the generic print function is called on a "waveband" object.

New convenience functions split_irradiance(), split_energy_irradiance() and split_photon_irradiance() for integrating unweighted irradiances for a series of contiguous wavelength ranges.

photobiology 0.2.15
===================
Updated NAMESPACE to fix error caused by changes in Rcpp or R.

photobiology 0.2.14 (2014-01-05)
================================
Updated User Guide. Modified interpolate_spectrum so that it uses cubic spline interpolation when the number of data points is small, and linear interpolation otherwise.

photobiology 0.2.13
===================
Moved peaks-related functions to new package photobiologygg and removed dependence on splus2R.

photobiology 0.2.12
===================
Added new functions find_peaks and get_peaks, which are wrappers built on top of function peaks from package splus2R, which becomes a new dependency.

photobiology 0.2.11
===================
Added Rcpp version of insert_hinges() using the much faster binary search algorithm.

photobiology 0.2.10
===================
Small, backward compatible change to trim_tails: added fill parameter. If NULL (default) the function works as earlier deleting the tails. If another value is passed as fill, the s.irrad values in the tails are replaced with this value.

photobiology 0.2.9
==================
Added two new functions: interpolate_spectrum() and sum_spectra()

photobiology 0.2.7 + 0.2.8
==========================
The vignette "Examples" was moved to a separate package because it used a very large data set. An "benign"" error in new_waveband() was fixed (this has no effect on calculations). The data set sun.data was updated to contain instantaneous data, and its documentation updated to better describe the data.

photobiology 0.2.6 (2013-08-27)
===============================

A vignette "Examples" was added. Other examples will be added later on. No changes to R or C++ code.

photobiology 0.2.5 (2013-08-11)
===============================

A vignette "Manual" was added. No changes to R or C++ code.

photobiology 0.2.4
==================

As profiling showed that calls to insert_hinges() and within this function to which() were using most of run time of the functions, a new parameter was added to functions so that the use of hinges can be switched on and off. The default is to use hinges for interpolation only if the wavelength resolution of the spectrum is worse than 1.0 nm. This causes only small errors in the results of calculations (< 1%) but reduces run time very significantly. The defaults should work just fine in most cases, in which case there is no need to do any changes to user code. In addition new_waveband() was modified so that if no SWF is used, then hinges are not included in the waveband defined.

photobiology 0.2.2-0.2.3
========================

Revised photon_ratio() to use same optimizations.

Improved implementation of cache. Now it is enclosed in an environment that is created when the package is loaded and removed when it is unloaded.


photobiology 0.2.1
==================

Factored to a separate function the code to check spectral data, and added argument to irradiance to switch off the checking.

Added a "name" field to wavebands and a wb.name argument to new_waveband(), with a default so that no old code will be broken.

Added argument to calc_multipliers() to enable caching. Disabled by default.

Added argument to irradiance() to enable/disable checking of spectral data. Enabled by default.

Added argument to irradiance() to enable use of speed optimizations.

Defaults to arguments ensure that nothing changes from earlier versions unless new features are explicitly enabled.

photobiology 0.2.0
==================

Reimplemented irradiance(), calc_multipliers, e2qmol_multipliers(), and added e2quantum_multipliers().
Also reimplemented new_waveband(), changing its interface. Some changes in other photobiologyxxxx will be needed.

photobiology 0.1.0 (2013-07-08)
===============================
