more work on RelaxNG streaming validation trying to improve the subset

* relaxng.c xmllint.c: more work on RelaxNG streaming validation
  trying to improve the subset compiled, and more testing.
* doc/downloads.html doc/xml.html doc/xmlmem.html: some updates on the
  documentation
* test/relaxng/tutor11_1_3.xml: fixes the DTD path
* result/relaxng/*.err: fix some of the outputs
Daniel
12 files changed