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
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
added px4flow integral frame, adjusted px4flow i2c driver, adjusted postition_estimator_inav
Fixed formatting of flow driver
Merged master
Formatting fixes
More formatting and cast fixes
More formatting fixes
Scan both buses
Kill last usleep()