title: Move in Word2Vec vector space in specific direction
body: <p>I've used gensim to train a Word2Vec model, and would like to query nearby terms. But instead of just getting the words that are closest in all directions:</p>
  
  <pre><code>model = models.Word2Vec.load('MyModel')        # load up my trained model
  nearest = model.most_similar(['mushroom'])     # nearby words all around
  </code></pre>
  
  <p>I want to move in a particular direction and distance within the vector space and retrieve the nearest word, essentially:</p>
  
  <pre><code>nearest = nearest_by_vector(word, direction_vector)
  </code></pre>
  
  <p>My vector math is terrible (ie non-existent), especially with so many dimensions in my model.</p>