As part of this, added emulation of the GD5428-based IBM 1MB SVGA Adapter/A,
along with support for external graphics cards on MCA platforms, adding the
ability to override the onboard VGA controller.
As part of this, added emulation of the onboard AVGA2, and fixed a couple of
bugs in the Cirrus Logic extended write modes.
Currently chipset (VLSI SCAMP) is missing EMS emulation.