perhaps should be part of the Model class?)

Also make vortex euler problem work

python/dune/femdg
that can be used for testing the different models and problems posed on
Cartesian meshes.

to the shallow water example. Can be seen when limiter tolerance is changed
from 1 to 1e-10

but cleaner for the user. Need to possibly reconsider.

LimiterDiscreteModel.

Highlight an issue with the diffusion timestep for IMEX method

Some issue with the boundary conditions need to be looked into

diffusionTimeStep.

provider.

Merge branch 'feature/dg-operator' of ssh://gitlab.dune-project.org:22022/dune-fem/dune-fem-dg into feature/dg-operator