title: how to change the etherpad's ace2editor to something else?
body: <p>i see that on <code>./etherpad/src/static/js/pad_editor.js</code> it's being called
  as,</p>
  
  <pre><code>  self.ace = new Ace2Editor();
  </code></pre>
  
  <p>can I just include and call some other editor (like codemirror) ?</p>