add methods to Word2Vec for word-word similarity
add methods to Word2Vec for word-word similarity

add a method to Word2Vec that returns the vector representation of a
word.
add a method to Word2Vec that computes the similarity between two words.

Signed-off-by: Ghassen Hamrouni <5dc9c287b62ebfa54650f34eb249280b9f206aa7@gmail.com>

summanlp/gensim,Kreiswolke/gensim,quole/gensim,zachmayer/gensim,gojomo/gensim,olavurmortensen/gensim,macks22/gensim,piskvorky/gensim,isohyt/gensim,RaRe-Technologies/gensim,dsquareindia/gensim,akutuzov/gensim,pombredanne/gensim,laic/gensim,mattilyra/gensim,isohyt/gensim,tzoiker/gensim,mattilyra/gensim,loisaidasam/gensim,dsquareindia/gensim,pombredanne/gensim,akutuzov/gensim,RaRe-Technologies/gensim,isohyt/gensim,loisaidasam/gensim,bhargavvader/gensim,ziky90/gensim,laic/gensim,robotcator/gensim,manasRK/gensim,jaksmid/gensim,markroxor/gensim,gojomo/gensim,zachmayer/gensim,quole/gensim,olavurmortensen/gensim,jaksmid/gensim,tzoiker/gensim,Kreiswolke/gensim,markroxor/gensim,davechallis/gensim,Kreiswolke/gensim,manasRK/gensim,summanlp/gensim,markroxor/gensim,gojomo/gensim,davechallis/gensim,macks22/gensim,ziky90/gensim,piskvorky/gensim,summanlp/gensim,piskvorky/gensim,RaRe-Technologies/gensim,ELind77/gensim,pombredanne/gensim,robotcator/gensim,akutuzov/gensim,dsquareindia/gensim,laic/gensim,bhargavvader/gensim,macks22/gensim,ziky90/gensim,olavurmortensen/gensim,mattilyra/gensim,ELind77/gensim,tzoiker/gensim,quole/gensim,ELind77/gensim,robotcator/gensim,gojomo/gensim,jaksmid/gensim,davechallis/gensim,manasRK/gensim,loisaidasam/gensim,RaRe-Technologies/gensim,bhargavvader/gensim,zachmayer/gensim