Enable a choice of the implementation in the UDV_C and UDV_R Routines
Fakher knows that he can't distribute the NAG implementation but still has grown accustomed enough to it so that he wants to retain it. Therefore we need to:
- remove the NAG Library
- port to Lapack
- While at it copy a reference implementation of lapack to it so it is comparable.
- introduce configuration switches for that choice
- (optional) select lapack SVD method? We could even retain that possibility at runtime