refactor for Codegen Routine

For OctaveCodeGen (pr #7824), I need some refactoring of `Routine`.

- [x] add Fortran matrix tests
- [x] add C matrix tests
- [x] move language specific stuff out of `Routine.__new__`

see this comment https://github.com/sympy/sympy/pull/7824#discussion_r17892414

On 30/09/14 03:50, Jim Crist wrote:
> If you feel like it, it'd be nice to clean these up if we're moving them around anyway.

Ok, I did a pass through the file.