RAS Preconditioner Code Up to A_i inversion

[KurtisAD]

Precond.txt

[CoreyPrachniak]

I tested the AS on a tridiagonal matrix. For delta = 1, 2, 3, the precond made iterations go from roughly 7000 to 30.
But the higher delta is the more iterations unfortunately. edit: now that I checked, this actually happened for their test 2/case 2