More cleanups in the keyboard drivers, especially the AT one (with new changes from 86Box.)
Small update to fix the CD sound volume when using SoundBlaster.
Updatd mem.c with new readmem386l and writemem386l functions from 86Box.
Several cleanups to the keyboard layer to remove some weirdness.
Updated the NVR code and nvr_at.c to just use a speed_changed member for the AT devices.
Devices now have a 'path' member, which usually points to a ROM file, or loader script.
No more 'available' functions unless one is needed for special cases.
Machines now can be 'configured' for mainboard settings etc.
Machines are now devices as well (root devices).
Regular devices now get a pointer to a 'parent' device.
The machines table has been reduced to just a lookup table, machine info is now inside the machine file.
Machine-specific CPU lists are now inside the machine file.
Chipset implementations are now devices, and were moved to devices/chipsets/
Much work on individual machines done.
All COMPAQ machines moved to dev-branch.
Zenith SupersPORT moved to dev-branch.
The i686-based machines (Tyan) released from dev-branch and cleaned up.
Several new MFM and RLL disk controllers for XT, in dev-branch for now.
