* Cleaned up zeus wave RAM accessors.
* Changed rendering code to allow for greater parallelism on multicore systems.
* Removed some vestigial zeus 2 hacks.
* Reduced visible area to remove artifacts.
* Made right/bottom vertices inclusive to fix some gapping issues.
* Fixed invasn lightgun offset.
* Marked invasn as playable.
Zeus 2 hardware:
* Fixed ROM loading, added banking support.
* Separated zeus 2 video implementation from zeus implementation.
* Implemented direct pixel accesses; enough to get startup screens to show.
ADSP-2100:
* Properly documented ADSP-2104 internal memory map.
Removed many hacks from both.
A couple of games changed status from GAME_NOT_WORKING to fully playable:
stagger1, redhawk, redhawkb, grdnstrm, spec2k, firehawk (all - former afega.c)
and tharrier/tharrierj(nmk16.c)
