* doc/Makefile.am doc/*.html doc/html/*.html: rebuilt the
  generated pages (again), manually restored doc/html/index.html
  and manually edited generated file doc/gnome-xml.xml to put
  in appropriate headings.
* doc/docdescr.doc: new file to describe details of the
  document generation (helps my memory for the next time)
* genChRanges.py,chvalid.c,include/libxml/chvalid.h: minor
  enhancement to please the automatic documentation generation.