Fix JacobiSVD wrt undeR/overflow by doing scaling prior to QR preconditioning
(grafted from d6bf18e70f68e738554cbf61576da70e2d99bea4)

--HG--
branch : 3.2
extra : source : d6bf18e70f68e738554cbf61576da70e2d99bea4
Fix SparseLU::absDeterminant and add respective unit test
(grafted from 0e64f7b3e7d70115247257d1d123a29491483df7)

--HG--
branch : 3.2
extra : source : 0e64f7b3e7d70115247257d1d123a29491483df7
Fix SparseQR::rank for a completely empty matrix.
(grafted from 1b9354d4370951e8cd66eac5df3eba34d05e44d6)

--HG--
branch : 3.2
extra : source : 1b9354d4370951e8cd66eac5df3eba34d05e44d6