Merge branch 'master' into bugfix/install_example_sources

.gitlab-ci.yml

dune.module

dune/fem-dg/algorithm/CMakeLists.txt

dune/fem-dg/algorithm/base.hh

dune/fem-dg/algorithm/caller/adapt.hh

dune/fem-dg/algorithm/caller/sub/CMakeLists.txt

dune/fem-dg/algorithm/caller/sub/adapt.hh

dune/fem-dg/algorithm/evolution.hh

dune/fem-dg/algorithm/gridinitializer.hh

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

dune/fem-dg/assemble/primalmatrix.hh

dune/fem-dg/examples/navierstokes/CMakeLists.txt

dune/fem-dg/examples/poisson/models.hh

dune/fem-dg/examples/stokes/models.hh

dune/fem-dg/examples/stokes/problems/corner.hh

dune/fem-dg/examples/stokes/problems/problem.hh

dune/fem-dg/examples/stokes/stokesalgorithm.hh

dune/fem-dg/misc/algorithmcreatorselector.hh

dune/fem-dg/operator/adaptation/adaptation.hh

dune/fem-dg/operator/adaptation/estimator.hh