title: SimpleXMLElement::addChild doesn't seem to work with certain strings
body: <p>In the effiliation pluggin for prestashop, i've found this code:</p>
  
  <pre><code>$values-&gt;addChild('marque', '&lt;![CDATA['.$product['manufacturer_name'].']]&gt;');
  </code></pre>
  
  <p>when in <code>$product['manufacturer_name']</code>, i have <code>Cyril &amp; Nathalie Daniel</code>, the output is <code>&lt;![CDATA[Cyril</code>,
  as opposed to the normal case: <code>&lt;![CDATA[Foo Bar]]&gt;</code></p>
  
  <p>Can the 2nd argument of <a href="http://php.net/manual/en/simplexmlelement.addchild.php" rel="nofollow">SimpleXMLElement::addChild</a> can contain <code>&amp;</code> ? Do i have to use some htmlentities on the manufacturer name ?</p>