initial commit of new HTML tokenizer
parse HTML comments
start of doctype parsing
more doctype tokenization

if we're going to be a standards-compliant tokenizer, we should know a doctype when we see one, as tedious as it is to implement.

If WHATWG wrote the JSON spec it would be at least 100 pages.
tokenize DOCTYPE
comment edit
tokenize (but no tags yet)
finish basic HTML tokenizer

no script data state yet, e.g.
Merge branch 'dgreensp-html' into shark-render2