Bunch of improvements in the device, memory and MMU handling.
Re-worked the NEAT 286 chipset (ported from VARCem).
Re-worked the ATI 28800 a bit, added Sierra SC1502x ramdac to VGA Wonder XL (Compaq) since it supports such.
Top 384K memory handling improvements (256K top memory too)
Added MCA version of MPU-401 (not tested much, however).
Re-worked the SCAT 286 chipset.
Fixed the segment address handling on both Tseng cards and also implemented register key protection for both - the real fix for the TSX scrolling problem (it appears TSX spuriously writes to port 3CD, probably to probe something, and that was messing up the banking segments).
The read and write bank addresses now follow the 256k wraparound - fixes scrolling in TSX on both the ET4000AX and the ET4000/W32p (needs further testing to make sure nothing is messed up by this).
A small change to how the video font array resetting is done, to correctly allow for internal Korean graphics cards, fixes the emulator segfaulting in some cases with the Trigem 286M and the internal Korean ET4000AX.
This shouldn't break existing configs. Existing "enable_sync" setings are automatically replaced with an appropriate "time_sync" value. In case "enable_sync" and "time_sync" settings are both present in a configuration file (shouldn't happen without manually editing the config), "time_sync" takes precedence.
Several bug fixes;
Preliminar addition of the SDL 2 renderer (does not yet work correctly in full screen mode);
SCSI devices no longer have configurable LUN's (this matches the configurability of real SCSI devices);
SCSI LUN's are now handed by the device's handler;
Removed all unused strings;
Removed some unused code files;
Significantly rewrote the bus mouse emulation.
Fixes to various hard disk controllers;
Added the Packard Bell PB640;
Fixed the InPort mouse emulation - now it works correctly on Windows NT 3.1;
Removed the status window and the associated variables;
Completely removed the Green B 486 machine;
Fixed the MDSI Genius;
Fixed the single-sided 5.25" floppy drive;
Ported a CPU-related commit from VARCem.
Changed the variables in the day of week calculation function in nvr.c from signed to unsigned, fixes the day of week calculation for dates in the previous century.
