The usemap attribute is currently treated as a boolean
by tidy. This is incorrect for all versions of HTML;
it should be (in source code terms) URL in VERS_FROM32,
and IDDEF in VERS_XHTML11.
The attached patch fixes this for VERS_FROM32, but
still produces incorrect results (ie. not checked as an
IDDEF) with XHTML11. Also a small comment fix is included.