This is a regression in functionality and performance, but a much better
foundation for the future of the project (I think). It can run basic
apps under an SSA interpreter but doesn't support some of the features
required to do real 360 apps yet.
This should make it easier to find files and (in the future) split things
up into separate libraries.
It also changes around emulator initialization to make it a little more
difficult to do things out of order and a little more sensible as to when
real init work happens.
Also adding a skeleton audio system/driver and reworking CPU register
access to be more extensible.
Not currently generating instructions, but most of the flow is right up to
that point. A lot of work required to refactor the emitter, but wanted to
get this checked in.