title: Vaadin: restrict available RichTextArea format options
body: <p>I would like to only allow the following format options in a RichTextArea</p>
  
  <ul>
  <li>Regular </li>
  <li>Bold</li>
  <li>Italic </li>
  <li>Subscript / Superscript</li>
  </ul>
  
  <p>I can't find any hints on how to do this. Except some information which is > 4 years old.</p>
  
  <p>Any help on how to archive this is highly appreciated. Thanks!</p>