DOM Level 3 DTD and Schema

Sorry I haven't been able to get a full wrap up of the DOM Level 1 issues.

I have updated build.xml so that you can build DTD and Schema for DOM Level 3 tests.  

The spec required an inordinate amount of patching as there were many entity declarations missing and a few files (core/xml/definitions/text.xml for example) that were missing.  You may manually need to copy text.xml from the Level-2 tree to the Level-3 tree, there is a <copy> statement, but didn't seem to work.

Hopefully, the next iterations of working drafts don't leave so many loose ends.  Look at level-3-version.patch and level-3-part-entities.patch for the missing entity declarations.