another patch from Brent Hendricks to add new handlers with the various

* python/generator.py python/libxml.py: another patch from Brent
  Hendricks to add new handlers with the various validity contexts
* python/tests/Makefile.am python/tests/validDTD.py
  python/tests/validRNG.py python/tests/validSchemas.py: also
  added the regression tests he provided
Daniel
10 files changed