Add basic application state to a class.
Add basic savestate support.
Add timers to the app struct.
Save and load timers into the savestates.
Factor out video state into an object.
Start persisting video settings on savestate.
Fix persisting video memory in savestates.
Fix video buffer writing to check for the app.
Push more global state into the app struct.
Persist the tvectors too.
Add a deterministic clock.

No longer does SheepShaver synchronize with the current clock; that can add
nondeterminism!
Add the start of recording/playback support.
Add recording playback; refactor recordings a bit.
Limit the processor to ~300KHz.
Bugfix in the F11 handler.
Add single-frame stepping.
Fix a race condition in ending single-frame stepping.