Very WIP version of using our own algorithm

TODO: implement Precond_Jacobi
Implement Precond_Jacobi
Fixes to Sparse_matrix class
omega and omega_precond are different things
Clear matrix between steps
Fix algorithm
Merge branch 'master' into wip/iter-ng
Cleanup unused code
Add back support for Laspack implementations (part 1)
Add back support for Laspack implementations (part 2)
Write diagonal elements to QMatrix