title: How to turn off save prompt when closing Sketchup
body: <p>I'm using sketchup with a plugin, which makes custom files. The users of this plugin never need to save their files of .skp files, and if they do it will confuse them.</p>
  
  <p>When closing Sketchup, there is a prompt to save the model, which would result in saving a .skp file, which is not desired. There is a <code>Sketchup::AppObserver.onQuit()</code>, but that doesn't full my purpose -- I'm looking for something more like <code>Sketchup::AppObserver.beforeQuit()</code></p>
  
  <p>any ideas?</p>