title: How to add a child to a node in a TreePanel?
body: <p>In a tree structure like this</p>
  <pre><code>var rootNode = { 
                id: 'root',
                text : 'Root Node',
      expanded : true,
      children : [
      {
          id :  'c1',
          text : 'Child 1',
          leaf : true
      },
      {
          id :  'c2',
          text : 'Child 2',
          leaf : true
      },
      {
          id :  'c3',
          text : 'Child 3',
          children : [
          {
              id :  'gc1',
              text : 'Grand Child',
              children : [
              {
                  id :  'gc11',
                  text : 'Grand Child 1',
                  leaf : true
              },
              {
                  id :  'gc12',
                  text : 'Grand Child 2',
                  leaf : true
              }
              ]
          }
          ]
      }
      ]
  };
  
  var tree = new Ext.tree.TreePanel({
      id: 'treePanel',
      autoscroll: true,
      root: rootNode
  });
  </code></pre>
  <p>How do I add a child node of any node (say 'grandchild')?</p>
  <p>I can access the child by traversing the root of the treepanel, but I console.logged it in Firebug, it does not have any functions.
  Sorry for the unformatted code, I was not able to format it.</p>
  <p><img src="https://i.stack.imgur.com/JS63b.png" alt="Tree Panel" /></p>