ManualControl: add arming on switch to options

New settings to allow configuring an Arming channel and assigning
it for arming.
ManualControl: allow a switch to control the arm/disam setting

This still runs through the checks for alarms so if you have a
system alarm going on it will not work.
ManualControl: enable disarm timeout for arming on switch

If ArmedTimeout is not 0, then when the transmitter goes away the
timeout will start counting down.  Reconnecting the transmitter
will immediately rearm the system.