Re-worked the system pathnames (pc.c), renamed cfg_path to usr_path.
Other small things here and there.
Logitech bus mouse re-worked, should be OK now.
IBM.H is gone, video stuff re-organized. Keyboard stuff reorganized.
Machines that have their own video, mouse and/or keyboard now have all this in their machine file.
Fixed and other cleanups here and there.
Fixed AHA-154x scatter/gather transfers;
Two-phased SCSI read-direction commands;
Made scsi_bus.c use a dynamically malloc'd buffer instead of a giant fixed-size buffer;
The AHA-154x/BusLogic thread now uses mutexes;
The BusLogic BT-545C is now the BT-545S;
Added the BusLogic BT-542BH;
The AHA-1542CF now again uses the v2.11 BIOS as the CD booting now works;
Applied PCem commit that adds NMI support to the recompiler;
Applied PCem commit that adds the IBM XT 286;
Applied PCem commits that have to do with sound, including the ES1371;
Fixed the NCR5380 output data register;
Moved the SLiRP mutex stuff from win.c to the appropriate network files;
Added sanity checks to everything in win_thread.c.
