title: jQuery UI Sortable, how to determine current location and new location in update event?
body: <p>I have:</p>
  
  <pre><code>&lt;ul id="sortableList"&gt;
       &lt;li&gt;item 1&lt;/li&gt;
       &lt;li&gt;item 2&lt;/li&gt;
       &lt;li&gt;item 3&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>I have wired into the <code>update: function(event, ui) { }</code> but am not sure how to get the original and new position of the element.  If i move item 3 to be above item 1, I want the original position to be <strong>2</strong> (0 based index) and the new position of item 3 to be <strong>0</strong>.</p>