Transmitter Control: Clean up some of the code for failsafe

The code in the transmitter module is not used anymore in the case
of a failsafe.
Transmitter Control: Refactor a bit

Added a short circuit exit from processing the inputs
which allows reducing an indent level.
Control: Fix arming / disarming

There were some miscellaneous bugs updating the old
arming code to insert events for the new control code,
and forgetting to update the lastSysTime.

Now arming/disarming works reliably.