Fixed issue #978 : Improved documentation of covariance coordinates transformation and shifting in StateCovariance
This mr aims to close issue #978 (closed).
However, I did not change the javadoc in the shiftedBy() method because I thought it was already pretty straightforward, what would you like to add exactly @Serrof ? Also, please tell me if the new javadoc of changeCovarianceType and changeCovarianceFrame are alright with you
Cheers, Vincent