title: Diffing only modified files in Mercurial
body: <p>In Mercurial it's possible to <code>hg status</code> only the modified/added/removed files by doing:</p>
  
  <pre><code>hg st -m
  hg st -a
  hg st -r
  </code></pre>
  
  <p>Is it possible to obtain the same behaviour for the <code>diff</code> command? From the man page, it seems not.</p>