Add tests of original functionality

Test with a few types of braces.

All tests pass.
Use solution from reddit that adds quote support

Instead of just braces, it closes quotes. This is trickier because they
are unmatched, so we need to do some magic to guess what's the right
thing.
Separate matched vs unmatched pairs

Reduce the duplication of the pair characters by separating the two
types into dicts that we can join into text classes.
Add support for angle brackets
Refactor synIDattr into is_string
Junk: Try to make string checking optional

Trying to be able to flip to the original (stackoverflow)
implementation, but I'm missing something because it doesn't work.