• getElementsById corrected to getElementById and the old name kept
  as an alias. Also re-implemented without XPath for improved
  performance
  
• DOM Level 3 method $attr->isId() added
  
• make {get,set,has}Attribute(Node)? methods work with full
  attribute names rather than just localnames.
  (Although DOM Level 3 is not very clear about the behavior of
  these methods for an attributes with namespaces, it certainly
  does not imply that getAttribute('foo') should return value of a
  bar:foo, which was the old behavior.)
  
• added publicId and systemId methods to XML::LibXML::Dtd