Merge branch 'release-0.8.7'
improve word2vec docs
first version of threaded word2vec
clean up, improve comments
replace ThreadPool with explicit threading
minor doc cleanup
BUG: Prevent overwrite of corpus and log warning
Changed warning to raising of ValueError
Reverted changes to test code...not necessary
also clean precomputed 2-norms when word2vec.reset_weights()
speed up word2vec vocabulary building
Merge pull request #124 from GHamrouni/develop

Add two methods to Word2Vec for word-word similarity
Merge pull request #125 from langmore/safe-save

Safe save
update support docs
pre-allocate work memory in word2vec threads
change numbering in FAST_SENTENCE
work around missing `with GzipFile()/BZ2File():` support in py<=2.6
* added metaclass that adds the necessary context methods
* used this metaclass in smart_open() for GzipFile and BZ2File, to avoid AttributeError: GzipFile instance has no attribute '__exit__' in older pythons
* closes #123
rename Word2Vec.cosine_simialrity to similarity, and get_vector_representation to [ ]
make sure input is utf8
cythonize job, not sentence