Merge branch 'feature/dg-operator' of...

dune/fem-dg/algorithm/evolution.hh

dune/fem-dg/algorithm/sub/advection.hh

dune/fem-dg/examples/advdiff/test/parameters/parameter

dune/fem-dg/examples/euler/algorithmcreator.hh

dune/fem-dg/examples/euler/euler.hh

dune/fem-dg/examples/euler/modelwrapper.hh

dune/fem-dg/examples/euler/test/CMakeLists.txt

dune/fem-dg/examples/euler/test/parameters/euler

dune/fem-dg/examples/euler/test/parameters/euler_wrapper

dune/fem-dg/examples/parameter/paramSolver

dune/fem-dg/models/additional.hh

dune/fem-dg/models/modelwrapper.hh

dune/fem-dg/solver/dg.hh

pydemo/euler/paramSolver

pydemo/euler/shock_tube.py