Added code submitted by Andreas Pakulat to provide node equality,

* python/libxml.c, python/libxml.py, python/tests/compareNodes.py,
  python/tests/Makefile.am:
  Added code submitted by Andreas Pakulat to provide node
  equality, inequality and hash functions, plus a single
  test program to check the functions (bugs 345779 + 345961).
5 files changed