Compile 8MHz version for the microRX.
Fix Sx outputs.
  - failsafe did not apply to them
  - the outputs only worked when telemetry was enabled
Make Sxx thresholds vary between outputs

This allows using one channel to control up to three separate
switches in following manner. The threshold is determined by
modulo of the output number, it is advisable to test the outpus
to verify order.

input     | SXa | SXb | SXc
-1166     | OFF | OFF | OFF
1166-1500 | ON  | OFF | OFF
1500-1830 | ON  | ON  | OFF
1830-     | ON  | ON  | ON