fink is a Macintosh package manager.
http://pdb.finkproject.org/pdb/browse.php?summary=tidy
shows their current tidy support, which doesn't include tidy-html5. as mentioned in #271.
In reading through the fink documents I couldn't figure out how on earth someone would submit a port or package suggestion to them, so this issue can be closed when fink is aware that tidy-html5 exists and someone decides to do (or not do) a port.