title: Auto scrolling in ExpandableListView
body: <p>I would like my <code>ExpandableListView</code> to automatically scroll when the user expands a group, so that the expanded group header is at the top of the screen. I've tried <code>smoothScrollToPosition</code>, but this merely ensures the expanded group is visible somewhere on the screen. I would like to explicitly scroll it so the expanded group is at the top, like in this example:</p>
  
  <pre><code>Before expanding Group 3:                After expanding Group 3:
  
  +=================+                      +=================+
  | Group 1         |                      | Group 3         |
  +-----------------+                      +-----------------+
  | Group 2         |                      |   Grp 3 Child 1 |
  +-----------------+                      +-----------------+
  | Group 3         |                      |   Grp 3 Child 2 |
  +-----------------+                      +-----------------+
  | Group 4         |                      | Group 4         |
  +=================+                      +=================+
  </code></pre>