move the TODO as comments as the function while not finished are usable

* xmlsave.c: move the TODO as comments as the function while not
  finished are usable as-is
* xmlschemas.c include/libxml/xmlerror.h: patch from Kasimier Buchcik
  implementing union
* test/schemas/union_0_0.x* result/schemas/union_0_0*: added example
* python/Makefile.am: applied fix from Mike Hommey
Daniel
9 files changed