applied a couple of patches from Martin avoiding some leaks, fixinq QName

* schematron.c xpath.c: applied a couple of patches from Martin
  avoiding some leaks, fixinq QName checks in XPath, XPath debugging
  and schematron code cleanups.
* python/tests/Makefile.am python/tests/xpathleak.py: add the
  specific regression tests, just tweak it to avoid output by default
Daniel

svn path=/trunk/; revision=3791