title: fabric center all objects as group
body: <p>I recently started to work with fabricjs, and I have a question about groups. I would like to center all objects (many) when canvas is resized. So I tought to build a group with all objects in my canvas and center it. </p>
  
  <p>However, in order to do that, I have to: </p>
  
  <ul>
  <li>retrieve all objects</li>
  <li>add them to my group</li>
  <li>remove them from my canvas</li>
  <li>add the group to my canvas</li>
  </ul>
  
  <p>A complex process, and, above all, my objects lost the possibility to be manipulate individually.</p>
  
  <p>I am wondering if it is possible to manipulate a group without add it in my canvas? </p>