The new code is based on timestamps, rather than delays. This eliminates the
need to update every timer in timer_process(), which cost a non-trivial amount
of CPU time on low-end machines.
This involved changes to every user of the timer code, so this change almost
certainly introduces bugs.
Added emulation of i430LX and i430FX chipsets.
Added support for PCI configuration type 2, used by i430LX.
Added AT disable keyboard command, and fixed enable keyboard command.
Added emulation of Intel 28F001BXT flash ROM, used by Advanced/EV.
Fixed a bug in REP when using multiple 66/67 prefixes.