20000324 :
	- added recursive defines. This means that the following is
	  now valid :
	  	define a 192.168.1.0/24
		define b 192.168.2.0/24
		define c a|b


	- added protocol "or". The following is now valid :
		
		 udp|tcp (local 2049) <-> (local 2049)


  	- added ip group, that is :

		tcp ((a|b) 2049) -> (any 2049)

  	  is valid and is the same as :

	  	tcp (a 2049 | b 2049) -> (any 2049)


  Thanks to Matthias Andree <ma@dt.e-technik.uni-dortmund.de> for these
suggestions

Older versions :  

 Thanks to Denis Ducamp <denis.ducamp@hsc.fr> for his suggestions.