Fixed bug that blocked some rules from being extracted. For example, the SENT::S rule in the following sentence pair was not extracted. (SENT (PP pp) (PP (N cours) (P de)) (. .))    (S (NP (NN course) (PP (IN of) (JJ next))) (. .))     0-2 1-0 2-1 3-3
Merge branch 'master' of github.com:armatthews/grex