Merge pull request #3 from nltk/master

Merge updates from NLTK master
Removed ParserI.prob_parse() and .prob_parse_sents()
Merge pull request #633 from heatherleaf/develop

Removed ParserI.prob_parse() and .prob_parse_sents()
Merge pull request #4 from nltk/develop

Pull from NLTK master into dougalg/nltk
Minor DocString Updates

Added docstrings for verbnet and wordnet packages
Merge pull request #636 from dougalg/master

Add docstrings for wordnet and verbnet
DOC reformat wordnet docstring to make it fit 72 chars