Enhanced filter command as discussed on forum

Enhanced filter command with chunk support, regex support, into clause and convert semantics, as discussed on the engine forum.
New syntax:
	filter [ ( lines | items ) of ] <container_or_exp>
	       ( with | without | [ not ] matching )
	       [ { wildcard | regex } [ pattern ] ] <pattern>
	       [ into <container> ]
The implementation is compatible with existing scripts.