title: Tokenizing texts in both Chinese and English improperly splits English words into letters
body: <p>When tokenizing texts that contain both Chinese and English, the result will split English words into letters, which is not what I want. Consider the following code:</p>
  
  <pre><code>from nltk.tokenize.stanford_segmenter import StanfordSegmenter
  segmenter = StanfordSegmenter()
  segmenter.default_config('zh')
  print(segmenter.segment('哈佛大学的Melissa Dell'))
  </code></pre>
  
  <p>The output will be <code>哈佛大学 的 M e l i s s a D e l l</code>. How do I modify this behavior?</p>