for the validation step but I have a clean way to add this without touching
the algorithm:
- valid.[ch] tree.h: worked *hard* to get non-determinist content
  validation without using an ugly NFA -> DFA algo in the source.
  Made a specific algorithm easier to maintain, using a single
  stack and without recursion.
- Makefile.am test/VCM/*.xml: added more tests to "make Validtests"
- hash.c: made the growing routine static
- tree.h parser.c: added the parent information to an
  xmlElementContent node.
Daniel