Added getCurrDevicePose() method in EKF.
(1) Created one test case for EKF in EKFTests.java
(2) Added covariance matrix getter function in EKF.java
(1) Corrected (untested) the addFeature() function in EKF. This also
included creating new sub-methods needed.
(2) Changed gyro to orient in IntegrateMotionEstimation.java