add extra check in VGA unchained handler regarding odd/even mode. the
extra check allows Windows 95's bootscreen to still work, while allowing
VGA planes to work properly. Prior to this fix, Windows 95 and Windows
3.1 exhibited glitches in 16-color planar mode. Also noteworthy, is the
fix for the Window 95 bootscreen also fixed conflicts between DOSBox
emulation and Windows 3.1/95 DOS boxes. You can now ALT+Enter into the
DOSBox, and ALT+Enter back out without VGA glitches.