Extend cg with left, right and split preconditioning
Add message in report for initial guess satisfying tolerance
Place two subsequent @devecs into a @devec block
Extend cgs with left, right and split preconditioning
Extend bicg with left, right and split preconditioning
Extend bicgstab with left, right and split preconditioning
Edit gmres reference
Update README.md
Make residual report of all Krylov methods consistent with resnorm
Merge branch 'preconditioning' into develop