HMC5883: Do not spam the console on error and make everything worse.
airspeed driver: Do not spam the console on error, report the system change only once
airspeed: Let the status check routine handle the initial state
add parameter to mavlink app to allow parsing of HIL GPS message even if not in HIL mode

Conflicts:
	src/modules/mavlink/mavlink_receiver.cpp
filter gps simulation hil gps message with sysid
add tags file to .gitignore
Merge pull request #862 from thomasgubler/gitignore_tags

add tags file to .gitignore
remove tags file
Merge pull request #860 from PX4/vicongpssimulation

Indoor gps simulation mode
Merge pull request #843 from PX4/sensor_err_handling

Sensor error handling