* fixes issue where indicators would flash when SBus RX entered failsafe
mode.
* fixes bug where turning off a TX for an SBus RX would instantly disarm
when using a switch to arm when the channel went outside the arming
range.
* introduces failsafe phases to make the system more understandable.
* allows the system to ask if rxSignalIsBeing received for all RX
systems: PPM/PWM/SerialRX/MSP. Also works when a serial data signal is
still being received but the data stream indicates a failsafe condition
- e.g. SBus failsafe flags.
* failsafe settings are no-longer per-profile.
Untested: Sumd/Sumh/XBus/MSP (!)
Tested: SBus X8R, Lemon RX Sat, X8R in PWM, Spektrum PPM.
Each flag was previously a whole byte, now all of the flags only take up
4 bytes as they are represented by bit masks.
This is cleaner because the different kind of flags are now separated.
Additionally this changes the behaviour of arming slightly. When using
a switch to arm the aircraft will not arm unless the switch has been in
the off state once. This prevents arming if you power the aircraft with
a low throttle and the switch in the on position.
