Adding reminder about Kahan matrix and reference to Golub and van Loan
Adding Kahan matrix and reference to Gu and Eisenstat's RRQR paper
Merge branch 'master' of https://github.com/poulson/Elemental
Almost there. Full compilation, passes every test but SequentialLU. (SequentialLU no longer crashes, but it doesn't get the right result, either.)