Fix 3 entries in mode tables related to mono and 90-column text modes.
Newer VGAs don't support any mono modes, but bugs in the tables created
2 virtual mono modes (#45 90x43 and #112 80x43) that behaved more
strangely than crashing. 90-column modes are tweaked 80-column ones
and also fail to work on newer VGAs. #45 did crash (hang) on some
hardware.