IIgs: Entering control panel resets DHR to color

[inexorabletash]

Repro:

1. Launch DeskTop on IIgs; note that DHR display is set to monochrome
2. Enter Control Panel (Ctrl+OA+Shift+Esc)
3. Exit Control Panel

Expect: Screen is still monochrome

Actual: Color!

Cause:

DeskTop twiddles NEWVIDEO bits directly. It should be modifying the BRAM bits as well.

https://groups.google.com/d/topic/comp.sys.apple2/FmncxrjEVlw/discussion and other threads have details.

[inexorabletash]

Alternately: just regularly set the mode back to B&W, for example in the clock update routine.

[inexorabletash]

I slipped this into the main loop, same frequency as updating the clock.

This won't work if the IIgs control panel is entered while the main loop is not running - e.g. during a DA or modal dialog - but the clock doesn't update either. Ah well.