DOM HTML tests

Switching gears from Core tests on HTML documents to HTML tests on XHTML documents.

I've updated http://home.houston.rr.com/curta/html-hacked-xerces.zip to support both HTML L1 and HTML L2 and made corresponding changes to the DOM HTML L2 suite.

To run the DOM HTML L2 suite with the hacked Xerces-J:

java -cp dom2-html.jar junit.textui.TestRunner org.w3c.domts.level2.html.TestXercesHTML

The test results look similar to those for the DOM L1 HTML.

Hopefully, this will allow Rick to fix problems common to L1 and L2 tests simultaneously.