An entity consists of a collection of zero or more LIBRARY files and one
PROGRAM file. These are distinguished by the first line, which must be
either

	Entity ENTITY-NAME ;

or

	Library LIBRARY-NAME ;




A collection of FUNCTIONS, which provide the intelligence and program
  code for the entity. The following functions are required:

	Initialise()	-	Called when the entity is created
	Destroy()	- 	Called when the entity is destroyed.

Typically, the Initialise() function will establish event handlers for
various external events and initialise any global data.

To access functions which are not defined inside the entity file, use 
the following external declaration:

	import LIBRARY1 ;
	import LIBRARY2 ;

before the declaration of the first function.
