adapted the libxml files for libxslt. regenerated the docs.

* doc/newapi.xsl, doc/api.xsl, doc/apibuild.py, doc/site.xsl,
  Makefile.am: adapted the libxml files for libxslt.
* doc/API*.html, doc/html/*.html, doc/libxslt-api.xml,
  doc/libexslt-api.xml, doc/libxslt-refs.xml,
  win32/libxslt.def.src, win32/libexslt.def.src: regenerated
  the docs.