title: Is there a way to override the Vorpal mode exit command?
body: <p>I'm using Vorpal <code>mode</code> to allow users to type in text, that I later parse (I couldn't find a way to do it with a regular <code>command</code> since I can't account for all text in advance). When the user types <code>exit</code> he's taken out of the mode. I'd like that to be a different string - or perhaps an additional string (say <code>quit</code> or <code>end</code>). </p>
  
  <p>Is there a way I can either override the <code>exit</code> command, or failing that, trigger it myself when a certain string is provided by the user?</p>
  
  <p>Sample code:<br>
  Here's an <a href="https://github.com/TravelingTechGuy/RPN/blob/master/index.js" rel="nofollow">exercise that implements a Reverse Polish Notation</a> calculator. If you look at the <code>handleInput</code> function (line 47), you'll see that I had to manually handle the <code>q</code> string and kill the process - where all I want it to do is behave like the mode's <code>exit</code> command (somewhere around line 74).</p>