Features added

• Module level iterwalk() function as 'iterparse' for trees
• ElementTree compatible iterparse() module function
• Element.nsmap property returns a mapping of all namespace prefixes known at the Element to their namespace URI
• Reentrant threading support in RelaxNG, XMLSchema and XSLT
• Threading support in parsers and serializers:
  • All in-memory operations (tostring, parse(StringIO), etc.) free the GIL
  • File operations (on file names) free the GIL
  • Reading from file-like objects frees the GIL and reacquires it for reading
  • Serialisation to file-like objects is single-threaded (high lock overhead)
• Element iteration over XPath axes:
  • Element.iterdescendants() iterates over the descendants of an element
  • Element.iterancestors() iterates over the ancestors of an element (from parent to parent)
  • Element.itersiblings() iterates over either the following or preceding siblings of an element
  • Element.iterchildren() iterates over the children of an element in either direction
  • All iterators support the tag keyword argument to restrict the generated elements
• Element.getnext() and Element.getprevious() return the direct siblings of an element

Bugs fixed