[NTVDM]

[NTVDM]
Rewrite the VGA emulation.

Nah, it's a joke!
- Store VGA registers setup in VGA_REGISTERS structure.
- Improve BiosSetVideoMode and introduce a VgaSetRegisters function for setting VGA regs.
- Initialize Bda->CrtBasePort: it is used to determine the address of some I/O ports which depend on whether we are in color or monochrome mode.
- Add UnregisterIoPort in io.c (and fix some DPRINTs) (needed for VGA).
- When setting the misc. VGA register, check whether we're going to monochrome emulation, and reset some port addresses in that case.

svn path=/branches/ntvdm/; revision=61246