title: Returning only the filtered tree from fancytree
body: <p>Please help.</p>
  
  <p>This is probably very simple, but I've been stuck on it  for days.</p>
  
  <p>As the title says, I want to get only the filtered tree including parent nodes in <a href="https://github.com/mar10/fancytree" rel="nofollow noreferrer">fancytree</a> (for <code>json</code> purposes).</p>
  
  <p>I've looked at <a href="https://github.com/mar10/fancytree/wiki/ExtFilter" rel="nofollow noreferrer">ext-filter</a>, but it doesn't seem to directly provide any <code>getRootNode</code> or <code>findAll</code> functions.</p>
  
  <p>How do I retrieve the filtered version of a tree?</p>