- no longer start sercon or mavlink usb by default
- on USB connection (VBUS) monitor serial USB at low rate and start Mavlink if there's a HEARTBEAT or nshterm on 3 consecutive carriage returns
- the mavlink USB instance is automatically stopped and serdis executed if USB is disconnected
- skipping Mavlink USB (and sercon) saves a considerable amount of memory on older boards
- generate PWM_MAIN 1-14
- generate PWM_AUX 1-8
- generate PWM_EXTRA 1-8
- px4io and pwm_out directly read configuration parameters
- only available and active physical outputs are actually shown for configuration
- overall saves flash despite adding many new parameters
- simple state machine to reset, configure, etc
- checked register mechanism (sensor will reset itself on configuration error)
- configured in 16 bit mode (1320 LSB/Gauss instead of 330 LSB/Gauss)
- adjusted orientation handling in driver to match datasheet as closely as possible
- in many external compass units the rotation was wrong and very difficult to actual determine how to set correctly
