Turn off default normalization of vectors in orthogonalize
Tests now test all reasonable matrix inputs over BlasFloats
- Adds type conversions as necessary to preserve type
- Adds KrylovSubspace constructor which resets an exisiting KrylovSubspace
Add size(A::KrylovSubspace, n), and f*v notation to mimic matvecs
Rename simple `ev_*` methods to `eigvals_*` for consistent nomenclature.
Rename KrylovSubspace.maxdim to .order
Basic documentation in README

- Documents KrylovSubspace, ConvergenceHistory and associated low-level methods (orthogonalize).
- Documents naming conventions.
Stable Givens rotation for GMRES