Support for header cells was mostly in already, just needed minor
changes. Added two tests as well.

Started support for parsing table style attributes. I suspect some
of this is incorrect, need to add more tests to see.

Added another stack layer for tokenizing table cells because of
styling/correctness of implementation. Added many tests cases.

Started parsing table support and added the start of table support.
This is a big commit (ugh) and it should probably be split up into
multiple smaller ones if possible, but that seems unworkable as of
right now because of all the dependencies. Also breaks tests of
CTokenizer (double ugh) because I haven't started table support there.

May want to pick line by line on this commit later but I need to save
my work for now.

- Add a test for very long strings of text.

Remove an now-unused import in the tokenizer.