added -parse-listener option, interfaces; fixes antlr/antlr4#18#22

Merged

parrt merged 3 commits intoantlr:masterfrom parrt:master

Feb 19, 2012

+247-168

Commits on Feb 18, 2012

Fix regression; did not gen enter/exit in alt label structs.
parrt
committed

Commits on Feb 19, 2012