fixes to Grammar.increment_tree -- now works.
Small tweaks on Performance
Merge branch 'master' of https://github.com/piantado/LOTlib
small tweak to increment_tree
Merge branch 'master' of https://github.com/piantado/LOTlib
merge from piantado/LOTlib, fix merge conflict in Grammar
comment out print statement in Grammar.py, add print statement in GrammarTest.py