Tilting allows using left/right rotated or invetrted display orientation.
This can be changed at runtime such as: echo tilt right > /dev/vgactl
This removes the old panning and vga overlays as they are only implemented
with some ancient vga controllers.
we have to reset hwblank when switching drivers to
prevent the generic vgablank() to be called by
blankscreen().
remove code setting hwblank from vga drivers as
devvga will always force hwblank to be 1 or 0
depending on if the driver provides a native blanking
routine.
set hwaccel to 1 when the driver provides native fill
and scroll routines independent of softscreen being
disabled. this allows hw acceleration to be used when
softscreen gets switched off.