more cleanup in make tests more work in the transition to the new error

* Makefile.am: more cleanup in make tests
* error.c valid.c parser.c include/libxml/xmlerror.h: more work
  in the transition to the new error reporting strategy.
* python/tests/reader2.py  result/VC/* result/valid/*:
  few changes in the strings generated by the validation output
Daniel
26 files changed