patch: domxml - set_attirubte_node implmentation

Here is a patch for domxml which implements the set_attribute_node method. Located at: http://www.digarc.com/php_domxml.diff One thing to note is in the section where an attribute already exists. As there can't be dunplicate attributes, only the content from the new attribute node is moved to the existing attribute node. Unlinking the origional attribute node could potential cause a memory leak as it may never be freed. Rob