Dynamic PAL/NTSC switching

Created by: sonninnos

Attempt at doing resolution and timing switching on the fly. It can be tested for example at Early Startup (hold LMB+RMB while booting A1200). Protracker also has a toggler.

If there is a way to achieve the same result without the desktop flashing, I'm all ears. I could not get the new timing to apply without using RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO, and that causes the flash. Geometry alone updates nicely without the flash.

If nothing else helps then maybe a core option should be added to disable the Hz change but allow the geometry change.

This will fix the double statusbar issue with Dyna Blaster (if the statusbar is at the bottom), but because it uses a weird 60Hz PAL mode (but acts like normal NTSC on a real Amiga), and it keeps returning to PAL for a split second during loadings for zero reason, it needed some trickery.

Also found more unused GUI stuff for removal.