Reverted Direct3D to 2048x2048 buffer and suppressed the EGA/(S)VGA overscan, if enabled, in 2048x modes, fixes Direct3D freezes;

Improved the BusLogic incoming mailbox code;
The BusLogic callback is now three-phases and outgoing mailbox interrupts are emulated correctly;
Fixed the CD-ROM command READ DISC INFORMATION (0x51), fixes NetBSD crashing 86Box with segmentation fault when using the AHA-154x;
Added the CD-ROM command PAUSE/RESUME ALT (0xC2).

src/ibm.h

@@ -607,3 +607,5 @@ extern int fdc_do_log;
 extern int ide_do_log;
 extern int ne2000_do_log;
 #endif
+
+extern int suppress_overscan;