MADE:
--> Started class PositionEstimatorNCamerasEKF. Modification of previous StereoVisionEKF  but for n cameras
MADE:
--> Added  GroundTrackingEKF
--> Moved creation of rotation matrix to Matrix.h and Matrix.cpp

TODO:
--> Test GroundTrackingEKF
MADE:
--> Tested ground tracking successfully

TODO:
--> Try to change ground tracking to one camera tracking or similar.
Merge branch 'EKF'
MADE:
--> Tested Release