title: ICommand vs RoutedCommand
body: <p>Let's have a button <code>Command</code> property bound to a custom command.</p>
  
  <p>When should I implement <code>ICommand</code> and when derive from <code>RoutedCommand</code>? I see that <strong>RoutedCommand implements ICommand</strong>.</p>
  
  <p>In which case could I need to implement an <code>ICommand</code>? 
  What about MVVM model? Which one suits better for this purpose?</p>