This added a fair bit of complexity, and notable made the Phase classes
dynamically generated.

However, by doing this, we no longer include "process the
token using the rules for" phases in the debug log.

This allows us to define the argument as an int in Cython

This is in preparation for Cython using C function pointers for _state

The current _ascii module is a placeholder, because I accidentally
deleted the original implementation of it (but I needed to rewrite it
to be even quicker anyway!)

This makes duplicate checking much quicker, and avoids the
conversion to a dict at the end