* SAX.c testXPath.c valid.c xmllint.c include/libxml/valid.h:
  allow to inherit attributes from the DTD directly in the
  tree, this is needed for XPath and can be a useful feature.
  Inherited namespaces are always provided at the tree level now
* test/defattr* result/defattr* result/noent/defattr*: added a couple
  of tests for this feature (XSLT being the prime user).
Daniel