Remove plot=True arguments from examples
Implement a ShallowWaterSolver and a DummySolver.

Also remove the thrust feature
Introduce the Problem class ShallowWaterProblem.

All but 4 tests are still failing
The parameters are now classes with attributes

Instead of dictionaries. This has the advantage that they can be nicely
documented with Sphinx. It should also be possible to thorow an error if a
non-existing attribute is written.
Implement a FrozenClass

This class does not allow new attributes. It will be used for the parameter classes.
Add a Dummy model problem
Remove shallow water options from configuration
Remove more options from the global config dict
Simplify ConstantFlowInitialCondition
Fix smeared test
Fix multi steady state test
Tidy up a bit
Fix dynamic control test
Fix all remaining tests
Remove an unused feature
Generalize boundary conditions, move fe space
Add missing file
Fix all remaining tests
Remove the fucntional integration from the solver
Fix multi-steady state test