driver for the TeraRangerOne I2C ranger finder
update attitude_estimator_ekf, includes matlab

This adds the latest c implementation (matlab coder) of
attitude_estimator_ekf, the .m matlab script and the .prj file with the
settings to export the matlab code to c
Merge remote-tracking branch 'upstream/master' into attitudeekf
att ekf: add param to enable/disable J
att ekf: add descriptions for params
Merge remote-tracking branch 'upstream/master' into attitudeekf
Merge remote-tracking branch 'upstream/master' into attitudeekf
Merge remote-tracking branch 'upstream/master' into attitudeekf
update attitude estimator ekf to latest version

mainly saves stack size
ORB topic for drive testing requests
cmd line utility for controlling drive tests
mavlink: use altitude AMSL in VFR message
commander: Added time of RC-loss/gain to the mavlink_log_critical message to better inform the user
commander: Added duration of rc-loss to mavlink_log_critical message
Enable IO safety parameter
Add a min PWM output so motors idle on arming.
Merge pull request #1400 from sjwilks/discovery_config

Add a min PWM output so motors idle on arming.
Formatting commander.cpp to simplify later rework by ensuring formatting match. NO CODE CHANGES
Merge pull request #1401 from PX4/commander_format

Formatting commander.cpp to simplify later rework by ensuring formatting...
Made some space for FDs - needs proper fix, but will give hackers some relief