title: php: strtotime("12/31/2004 +6 month")); not returning the last day of June
body: <p>I expected this functional to return <code>6/30/2005</code> instead of <code>7/1/2005</code>.</p>
  
  <pre><code>print date("m/d/Y", strtotime("12/31/2004 +6 month"));
  </code></pre>
  
  <p>Similarly, <code>print date("m/d/Y", strtotime("1/31/2011 +1 month"))</code> returns <code>03/03/2011</code> while would like it to return <code>2/28/2011</code>.</p>
  
  <p>Does anyone know if there is a straight forward way to show the last day of the added month? </p>