title: Marionette CollectionView: how to check whether item is added because of "reset" or "add"?
body: <p>I am using Marionette's <code>CollectionView</code> to render a list of items with <code>ItemViews</code>. Whenever a new item is added, I want to run a short fade-in animation. But not when the collection is rendered initially (or the collection is reset).</p>
  
  <p>Before using Marionette, I handled the <code>reset</code> and <code>add</code> events slightly differently, but I can not figure out how to do this here. I looked at the source code and it seems that <code>addItemView</code> is responsible for adding the child view and both <code>addChildView</code> (called when <code>add</code> is triggered on the collection) and <code>render</code> (for <code>reset</code> events) call this method.</p>
  
  <p>Maybe I am missing something obvious.</p>