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
Merge master into attitude EKF update