title: Parsec does not recognize block comments
body: <p>I have a problem with Parsec recognizing comments when parsing mustache templates.<br>
  The various mustache tags all start with <code>{{</code> include the block comment (<code>{{!comment}}</code>).
  I have set commentStart and commentEnd to <code>{{!</code> and <code>}}</code> in my TokenParser.<br>
  Whenever I add comments to a template, Parsec complains that the comment is unexpected.<br>
  It expects a mustache variable instead, since that is the only token that matches <code>{{</code>.</p>
  
  <p>When does Parsec remove comments? I thought it would happen before the source hits my parser?</p>