Updated to ANTLR 4
Merge branch 'master' of github.com:jrguenther/shiro
Added sample code for testing parts of the grammar
Updated pom to use ANTLR 4.1
Added ANTLR4 grammar
Removed bangs from grammar
Upgraded to antlr 4.1 from 4.0
Added basic definition pass and graph building pass
Add pass code
Added beginnings of expression events
Graph only test file
Added node production listener
Interpreter now works with ANTLR4