Update token capitalization & usage

# Overview
Upstream changes to naming / tokenizing made things easier, but
necessitated changing the token analysis code. Some legacy manual
span analysis code may still exist.

# Notable changes
Most things are just renames - pretty straight-forward.

Only thing that really changed was one logic check to check for `[]` delimiters in the generator macro. I had to change the checking to an if statement, to avoid copying referenced fields out of the `Delimiter` parameters.

# Caveats
Since the upstream changes are post-0.12, you'd have to have a recent version of rust for this to work. We could try to support older versions, but hey, this is rust, where we throw away all legacy support at the moment.