Misc ViRGE fixes.
Changes to memory mapping.
Changes to PCI handling.
Disabled 'AMI WinBIOS 486 PCI' due to incomplete chipset emulation.
Invalid GUS register reads no longer kill the emulator.
Seperated TGUI9440 and TVGA8900D implementations.
Modes > 8 bpp now handled more logically in SVGA core.
Fixed broken status window for most SVGA cards.
Masking of address on 'legacy' VGA memory ranges now handled better.