Output disabled on boot until gyro calibration complete

[dlktdr]

This should be changed so that the old gyro calibration values are used and output isn't ever disabled. If a reboot is needed mid flight I would want the output to still work, even if it's not perfectly accurate.

Scanning should always happen even in normal operation, if sitting still long enough, compare with the saved values. Only update if the calculated & saved differ by xxx (save on flash writes). Maybe >1.0 deg/sec