Working:
- Driver block
- Solving and visualization

Not working:
- Error calculation

[ ] Go through system part -> GFS
[ ] Export boundary grid function

So far, we had the opcounter cast to Dune::FieldVector
of size 1. Now it defines the correct type.

Instationary stuff not fixed so far.

Do not annotate FiniteElements anymore, further split driver code

We never really used or trusted it.

Do not annotate FiniteElements anymore, further split driver code