GXemul Code2

Minor documentation improvements.

ARCS environment fixes (better values for diskless booting).

Some cleanup and refactoring of the O2 rendering engine and other things.

Minor SGI O2 fixes and comments.

Minor fix for NetBSD crmfb_fill_rect: x is shifted 16 bits, not 12 bits.

Only allow SGI O2 MTE memory fills to pages that are in a TLB.

Made the pckbc work with NetBSD/sgimips.

Quieter.

Use SRC TLB, not DST, to read from. :-)

Implementing MTE_MODE_COPY in the SGI O2 memory transfer engine to allow NetBSD to scroll up the framebuffer.