title: symfony render a template/partial in a form
body: <p>I am trying to render a template in a form using the <code>_toString()</code> method.
  The problem I am facing is that the form does not inherit from controller and I can not do 
       $str.= $this->renderPartial('template',array('form' => $this));
  How can this be achieved ?</p>
  
  <p>I am using symfony 1.4 with PHP 5.3</p>