Bidiagonal Decomposition

Hi Mike,
I only added ```BidiagonalDecompositionRow``` because that seems sufficient for SVD, but I can add ```BidiagonalDecompositionTall``` later.
I tried to follow the convention being used Vectorz but I think they could be named better. Having the word 'decomposition' in them would look better in my opinion.

There are a couple of  things in particular I need your help with. There is a ```getUBV``` method on line 92 and a ```getDiagonal``` on line 97 in class ```BidiagonalRow```. Should those methods be there or in the result class? Also, ```getDiagonal``` takes two arrays and copies the answer into them. I thought it would be better if it didn't take any inputs and returned the answers but it can't return two things. Is there any fix for that?