sensors: add baro calibration and cleanup

- sensor_baro.msg use SI (pressure in Pascals)
 - update all barometer drivers to publish directly and remove PX4Barometer helper
 - introduce baro cal (offset) mainly as a mechanism to adjust
relative priority
 - commander: add simple baro cal that sets baro offsets to align with
GPS altitude (if available)
 - create new sensors_status.msg to generalize sensor reporting

src/lib/drivers/magnetometer/PX4Magnetometer.hpp

@@ -47,7 +47,6 @@ public:
 	void set_device_id(uint32_t device_id) { _device_id = device_id; }
 	void set_device_type(uint8_t devtype);
 	void set_error_count(uint32_t error_count) { _error_count = error_count; }
-	void increase_error_count() { _error_count++; }
 	void set_scale(float scale) { _scale = scale; }
 	void set_temperature(float temperature) { _temperature = temperature; }