* stat/*: Update functions to take empty matrices
Change TorgersonScaling to require an empty matrix. Users who want to reuse data can call Reset now that it is exposed. This function is different than others because the return size is unknown. Forcing the input matrix to be empty makes it clear that the dst matrix will be dynamically resized
Fixes#1081.
This avoids the confusion between Zero() and IsZero() which sounds like they should be related
to one another but are not. This makes IsEmpty the counterpart to Reset. Add check for Zero in allMatrix
Fixes#1083.
Updates #1081.
blas64: add length field N to Vector
Alongside, fix the implementation of mat.VecDense and mat.Diagonal, as well as other changes needed to fix this change.
Fixes#736.
