MatVec invChol check for failure
The merge request adds a mask to the return of MatVec's matrix inversion via Choleksy decomp. The mask flags the success of the inversion and leaves it up to the caller what to do. In many cases I chose to return NaNs after inversion failure, or pass on an already existing failure mask.
Goes with Rec!3798 (merged) and Moore!3273 (merged)
Closes Moore#740 (closed)
Edited by Andre Gunther