#3 Add full C800 expansion card ROM support

[CM]

Currently GSport lacks full emulation support for the Apple II C8 expansion card ROM protocol. Ideally virtual add-on cards should be able to use the 2K of ROM space at $C800-CFFF. Currently the emulator only maps the appropriate area of the Apple IIgs ROM in this space.

[David Schmidt]

The way memory is dealt with in engine.c makes this impossible at the moment.