GXemul Code2

Better memory bank stuff for SGI O2 (128 vs 256 MB RAM).

Fixing some 8242 key encodings (used by the SGI O2 mode).

Updating the OpenBSD/sgi installation instructions (still in unsupported.html though, and still only diskless).

Minor interrupt improvements (when debugging OpenBSD/sgi ethernet access).

Adding a horrible hack to enable the use of a RAM_MIRROR at 0x40000000 (for SGI O2 emulation). Also making some loops waiting for CRIME_TIME faster, and adding some comments.

Comment.

Refactored the register representation in dev_sgi_ip32 crime interrupt controller.

Updating TODO regarding O2 progress.

Comment.

Splitting the O2 GBE into a GBE part and a Rendering Engine part.