title: DateTime difference operator considers daylight saving?
body: <p>As far as I know the difference operator of the <code>DateTime</code> type considers leap years: so </p>
  
  <pre><code>new DateTime(2008, 3, 1) - new DateTime(2008, 2, 1) // should return 29 days
  new DateTime(2009, 3, 1) - new DateTime(2009, 2, 1) // should return 28 days
  </code></pre>
  
  <p>But what about daylight saving?</p>