HTML compatible Core tests

I've committed 196 tests in tests/level1/core that are transliterations of the existing L1 Core tests to use hc_staff.xml.  hc_staff.xml and hc_staff.html are valid, but nonsensical, [X]HTML files created by replacing the tag and attribute names in staff.xml with XHTML tag and attribute names.  HTML compatible tests all start with an "hc_" prefix followed by the name of the base test.

HTML equivalents of tests involving extended interfaces (ProcessingInstruction, Entity, EntityReference, Notation) and DocumentType's were not added since HTML implementations are not required to implement them.

My personal build of Xerces-J passes all the hc_* tests which should be equivalent for the purposes of these tests to a build from the Xerces-J CVS.  I have fairly high confidence that the tests are good XML tests, however I suspect there is a decent amount of tweaking ignoreCase attributes to make them good HTML tests.  The next step in the evolution of these tests is to build the JSUnit equivalents and test them with XHTML and HTML implementations.

I've added support for JTidy which provides a DOM L2 Core (but not HTML) implementation for HTML (but not XHTML) files.  However JTidy's DOM implementation is incomplete and can't be currently used as a reference implementation.  To run it download JTidy from http://sf.net/projects/jtidy and place tidy.jar in the same directory as dom1-core.jar and run "java -cp dom1-core.jar junit.textui.TestRunner org.w3c.domts.level1.core.TestJTidy"  The previous (non hc_*) tests are not suppressed (yet), so they should fail and quite a few of the hc_* tests fail.