[xml] bug in xmllint --htmlout. bug in README.

[Dan Kegel <dkegel ixiacom com>]

xmllint --htmlout sends the html wrapper to
stderr, but the body to stdout.  This
makes it kind of hard to use.

Also, the file README says

To report bugs, follow the instructions at:
  http://xmlsoft.org/XSLT/bug.html

but that URL is missing in action.  it should probably be
  http://xmlsoft.org/bugs.html