title: setting selection for multiple items in a QTreeView
body: <p>So I've been using :</p>
  
  <pre><code>treeView.setCurrentIndex( index ) 
  </code></pre>
  
  <p>to set the active item in my treeView.  But if I have an array of item indices that I would like to select, how do I add to my currently selected item?</p>
  
  <p>Thx!</p>