title: Use Xcode 4 as Git difftool
body: <p>I want to use Xcode 4's "Version Editor" view as my standard difftool for Git.</p>
  
  <p>In other words, I want to be able to set this option:</p>
  
  <pre><code>git config --global diff.external &lt;XCODE&gt;
  </code></pre>
  
  <p>And have the diff open in Xcode's diff viewer (because it's cool).</p>
  
  <p>Is this possible? How?</p>