Fix existing HTML support and add new standards.

* Replace the existing HTML support with code generated from the
  DTDs.  One exception is HTML5 which does not use SGML.

* Revamp HTML5 support manually by going through the W3C CR indices.
  Separate W3C HTML5 from WHATWG HTML5.

* Replace links to w3schools with the standards (see w3fools).

* Rename removeDash to removeSpecial as it also needs to remove colons
  from XHTML attributes.

* Add Html2 (2.0), Html3 (3.2), XHTML 1.1, and Html5WG (for WHATWG).