Added card save/load for:
. Phasor (#260)
. CP/M (#260)
. 80 column card:
. aux memory now saved separately from main memory
. extended memory (RAMworks) (#260)
Mockingboard & Phasor:
. Full AY8910 internal state now preserved.
. needed for eg. envelope, ay_change[], etc
. also Phasor player only updates AY regs that have changed
Other:
. On restore error, then PostMessage(WM_USER_RESTART), so that emulator not left in intermediate state
. Fix: Start Dir wasn't set when drag & dropping an image onto a drive icon or double-clicking an image file
