title: How to create a FormType without any entity?
body: <p>I just created a new form in <code>AppBundle/Form/Type</code> named <code>ContactType.php</code></p>
  
  <p>It's just a form with a field email and message, to send an email.</p>
  
  <p>How can I instantiate this form in my controller (I don't have any entites linked with) ? I tried somethings like :</p>
  
  <pre><code>$form = $this-&gt;createForm(new ContactType());
  </code></pre>
  
  <p>But symfony wants a string for argument of <code>createForm()</code>... Thanks !</p>