Description:
------------
If you add a new namespace to a document root with addAttribute(), the function incorrectly also tries to add a namespace for the new namespace, resulting in a spurious "xmlns:xmlns" attribute.

Add attribute called "foo:bar"
xmlns:foo="namespace-url" foo:bar="value" <-- correct

Add attribute called "xmlns:bar"
xmlns:xmlns="namespace-url" xmlns:bar="namespace-url" <-- incorrect

A special case is thus needed to ensure that, if the attribute name starts with "xmlns:", a namespace is not added for it:
xmlns:bar="namespace-url" <-- correct

Alternatively, a new function for adding namespaces to a document?


Test script:
---------------
<?php
$xml = new SimpleXMLElement('<office:document-content xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0"/>');
$xml->addAttribute('xmlns:ooow', 'http://openoffice.org/2004/writer', 'http://openoffice.org/2004/writer');
echo $xml->asXML();
?>



Expected result:
----------------
<?xml version="1.0"?>
<office:document-content xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0" xmlns:ooow="http://openoffice.org/2004/writer"/>


Actual result:
--------------
<?xml version="1.0"?>
<office:document-content xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0" xmlns:xmlns="http://openoffice.org/2004/writer" xmlns:ooow="http://openoffice.org/2004/writer"/>