- checked register mechanism and simple watchdog
- driver checks for errors gradually and can reconfigure itself
- respect IMU_GYRO_RATEMAX at the driver level
- fixed sensor INT16_MIN and INT16_MAX handling (y & z axis are flipped before publishing)
- increased sensor_gyro_fifo max size (enables running the driver much slower, but still transferring all raw data)
- PX4Accelerometer/PX4Gyroscope remove unnecessary memsets