Dumux course tasks

See merge request !553

Kilian Weishaupt authored 7 years ago and Timo Koch committed 7 years ago

* Dune > 2.5 uses a new interface and only required GridView as template
  argument for the mapper type
* for the constructor, an additional argument is now required:
  elementMapper_(gridView, Dune::mcmgElementLayout())
  vertexMapper_(gridView, Dune::mcmgVertexLayout())

(cherry picked from commit 6b4dc071)