Log Message:
update to 2.6.16

2.6.16: Nov 10 2004:
   - general hardening and bug fixing crossing all the API based on new
    automated regression testing
   - build fix: IPv6 build and test on AIX (Dodji Seketeli)
   - bug fixes: problem with XML::Libxml reported by Petr Pajas,  encoding
    conversion functions return values, UTF-8 bug affecting XPath reported by
    Markus Bertheau, catalog problem with NULL entries (William Brack)
   - documentation: fix to xmllint man page, some API function descritpion
    were updated.
   - improvements: DTD validation APIs provided at the Python level (Brent
    Hendricks)