[rotorcraft] CAUTION! stabilization int_quat ref model scaling fixes

Now the attitude reference should finally have the correct scaling.

For end users that means it is not so sluggish on RC input anymore and you should get a snappy reference.
CAUTION! Test fly carefully, you might need to lower the gains.
[rotorcraft][stabilization_ref_quat] saturate rate and trim accel
[conf] stm32f4 discovery test board files
[conf] updates for fraser quad with spektrum
[rotorcraft] PRINT_CONFIG_VAR for GUIDANCE_V_NOMINAL_HOVER_THROTTLE