title: cast List object to new object extending List
body: <p>I'm trying to generate a custom xml doc, using this class:</p>
  
  <pre><code>[CollectionDataContract(Name="Applications", ItemName="Application")]
  public class ApplicationNamesList : List&lt;string&gt; { }
  </code></pre>
  
  <p>The xml output im aming at should look like this </p>
  
  <pre><code>&lt;Applications&gt;
      &lt;Application&gt;...&lt;/Application&gt;
      &lt;Application&gt;...&lt;/Application&gt;
      &lt;Application&gt;...&lt;/Application&gt;
  &lt;/Applications&gt;
  </code></pre>
  
  <p>But once I have a <code>List&lt;string&gt;</code> object and try and cast this to <code>ApplicationNamesList</code> i get an <code>InvalidCastException</code>. </p>
  
  <p>Is there something basic im not getting here?</p>