Refactor: g_bVideoMode -> g_uVideoMode
More main-loop reduction & removal of redundant globals.

Fixed JoyUpdateButtonLatch() to debounce in 5mecs instead of 5secs!

SpkrToggle() was using redundant global ('cyclenum') when using the PC speaker.
. I reworked the code (as it looked out-of-date),
    but probably better to just remove all the PC speaker support.