title: cytoscape.js zoom to fit currently selected nodes
body: <p>I wish to zoom the cyjs view to fit (nicely contain)  the currently selected nodes.  nodes could be selected manually, or programmatically.  If only a small network neighborhood has been selected, then the zoom-in would be pretty dramatic.  If distant nodes are in the selection, then the zoom in might not even be noticeable.</p>
  
  <pre><code>cy.fit(&lt;padding&gt;) 
  </code></pre>
  
  <p>works great to display the entire network within the window.  But try as I may, I cannot find</p>
  
  <pre><code>cy.fitSelected()
  </code></pre>
  
  <p>or some functional equivalent.</p>
  
  <p>Suggestions, anyone?</p>