title: collapsing/expanding compound node in cytoscape
body: <p>Does cytoscape.js support collapsing/expanding compound node ?</p>
  
  <pre><code>Eg. before collapsing
  
  node1 (-)
  --node1.1
  --node1.2
  ------node1.2.1
  </code></pre>
  
  <p>After collapsing <br></p>
  
  <pre><code>node1 (+)
  </code></pre>
  
  <p>A (+) or (-) sign to expand/collapse would be great.</p>
  
  <p>Looking for options to Group a set of nodes using Compound node and collapse/expand via user-interaction. If cytoscape.js doesn't support this by-default, any alternatives/workarounds to reach the goal ?</p>