Rover: added SERIAL0_BAUD parameter
AP_InertialSensor: update PX4 driver to use read() method
HAL_PX4: fixed thread_running on failed startup
build: added configure_px4fmu to clean target
Copter: fixed test code warnings
Plane: run PX4 console at 57600
Plane: fixed test baro printout
AP_Baro: added accumulate method to PX4 driver, and fixed scaling