title: Tesseract problem with mftraining stage
body: <p>I've successfully created a box file with tesseract <br>
  now after running the unicharset_extractor <br>
  having it creating the unicharset file that looks like:</p>
  
  <pre><code>...
  n 3 NULL -1
  s 3 NULL 23
  t 3 NULL 43
  ...
  </code></pre>
  
  <p>I've continued with this command</p>
  
  <pre><code>mftraining -U unicharset -O testlang.unicharset testlang.tr
  </code></pre>
  
  <p>only to get the next error</p>
  
  <pre><code>Reading testlang.tr ...
  testlang has no defined properties.
  
  Error: Illegal short name for a feature!
  </code></pre>