Getting XHTML 1.1 Working

It's quite simple, according to <http://www.w3.org/TR/xhtml11/changes.html>

1. Scratch lang entirely in favor of xml:lang
2. Scratch name entirely in favor of id (partially-done)
3. Support Ruby <http://www.w3.org/TR/2001/REC-ruby-20010531/>

...but that's only an informative section. More things to do:

1. Scratch style attribute (it's deprecated)
2. Be module-aware (this might entail intelligent grouping in the definition
   and allowing users to specifically remove certain modules (see 5))
3. Cross-reference minimal content models with existing DTDs and determine
   changes (todo)
4. Watch out for the Legacy Module
<http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410/abstract_modules.html#s_legacymodule>
5. Let users specify their own custom modules
6. Study Modularization document
<http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410/>