This reduces the number of rubbish pulses on the APM2 PWM output pins
on startup, which should help with booting some cheaper ESCs.
Thanks to Randy for the idea!
this allows logging of the actual servo output values. The radio_out
method previously used doesn't take account of the various override
mechanisms available via waypoints
* CH_10 is on APM2 pin A10 (based on A1..A8 convention)
* CH_11 is on APM2 pin A11
* Only the code in enable_out, disable_out, and OutputCh needed to change.
* CH_10 and CH_11 always have an output period of 20ms (50Hz).
* Every use of MSK_CH_n changed to _BV(CH_n)
* Easier to read, and will allow CH_n to be parameterized without needing
a separate macro expansion for the MSK value.