Renamed wff.g4 to Wff.g4
Merge branch 'master' of ssh://github.com/PeterDrake/Logic

* 'master' of ssh://github.com/PeterDrake/Logic:
  Added other characters per Eddie's request
  More minor fixes
  added highlighting of errors
  More minor updates
  Renamed grammar file, fixed TestButton exception possibility
  Error handling works! Using exceptions, proper error messages, etc