Changes in CADKEY LISP since the writing of the manual.

1.  (ssfree sset)
	The 'ssfree' function has been added to free the use of a selection set
	once it is no longer needed.  CADKEY LISP, at the time of this writing,
	does not perform automatic garbage collection on selection sets. Therefore,
	it is necessary to free the selection set when it is no longer needed.

2.  Determining the 'Host CAD system'.
	If you will be writing LISP code to be used on more than one CAD system,
	you may wish to know which system the LISP code is running on.  This
	could enable the use of enhancements not available on other systems.
	By performing a (getvar "CKVER"), it can be determined if CADKEY is 
	being run.  This system variable will return nil on all other CAD systems,
	but should return the current CADKEY version when running with CADKEY.

