= power-cycle-safe calibration
- on power up, rx has control over servo immediately. apply the mixer (eg. delta/vtail) but do not apply stabilization (gyro/gain).
- calibrate imu only if it is still (100 consecutive samples).
- calibrate (rx) sticks only if they are still (100 consecutive samples).
- enable stabilization only after calibration is complete.
- led output to indicate calibration state
> 1 short (200ms) flash = rx calibrating
> 2 short flashes = imu calibrating
> 3 short flashes = both calibrating

= generate builds files
- RX3S_V1_20130119.hex
- RX3S_V2_20130119.hex

= some more naming and minor cleanups

= this new code exposed a bug in the rollover test. i think the old test tried to verify a non use case (where the "t - last_t"  interval test exceeds 2**31us, which should never be the case). i'll look into the rollover test again (perhaps all high order bits including the bit 31 ovf needs to be set)
Merge branch 'master' of https://github.com/noobee/FlightStab