Changelog:

Revision 1250: MTVC/MFVC: - added code to get/set VFPU_PFXS, VFPU_PFXT and VFPU_PFXD registers.
Revision 1249: Further findings for Video command CLEAR (based on tests using 3D Studio): also
disable CULL_FACE, FOG, STENCIL_TEST, COLOR_LOGIC_OP and DepthMask in CLEAR
mode.
Revision 1248: Improved color accuracy for vertex color formats 5650, 5551 and 4444.
Revision 1248: Provide basic implementation for MFVC and MTVC