title: Compile coffeescript Ext.js Ext is not defined
body: <p>I'd like to use coffeescript in an Ext.js project. What do I have to do in order to make the compiler to know the Ext namespace?
  Whenever I compile an ext-js.coffee with node I get the error Ext is not defined</p>
  
  <pre><code>Ext is not defined
  </code></pre>
  
  <p>I'm sure it's a ridiculously easy to solve issue, but I'm stuck in a think-stack-overflow.
  Any help is much appreciated.</p>