Merge pull request #7 from dane-unltd/master

transpose matrix internally to allow SVD on wide matrices

Fixes issue #5.

TODO(kortschak) Add tests and clean up comments regarding new behaviour.
Complete fix for issue #5

This updates the comments describing SVD behaviour and ensures that the
correct matrices are constructed.

Output disagrees with R's svd function in sign only.
Allow Rank and Cond to work without U or V

Previously we obtained the dimension of A from U and V rather than just
keeping them internally. This prevented Rank and Cond being used if
those matrices were not requested.
Remove caveat about shape on Norm since Issue #5 is fixed
Add views on rows

This was suggested in PR Issue#6. Here it is used to simplify
Vectorer-based operations. The next commit will use it in place of
Row/SetRow pairs in decomposition functions.
Reduce copying in decomposition functions
Reduce the number of copy operations in pivotRows
Reduce cost of row operations in QR

It is not obvious how to get similar optimisations into the Q'B
operation without allocation, so I'm leaving that.