title: HTMLPurifier removes target="_blank"
body: <p>I'm using HTMLPurifier and even thou I have :</p>
  
  <pre><code>$config-&gt;set('HTML.Doctype', 'XHTML 1.0 Transitional');
  </code></pre>
  
  <p>it removes all 'target' attribues from the links.</p>
  
  <p>Any idea why is it doing it?</p>