Merge branch 'master' into feature/parametertreeconstructor

.gitlab-ci.yml

CHANGELOG.md

cmake/modules/DuneIstlMacros.cmake

cmake/modules/FindSuperLU.cmake

doc/CMakeLists.txt

doc/istl.tex

dune/istl/CMakeLists.txt

dune/istl/bcrsmatrix.hh

dune/istl/bdmatrix.hh

dune/istl/btdmatrix.hh

dune/istl/bvector.hh

dune/istl/cholmod.hh

dune/istl/colcompmatrix.hh

dune/istl/gsetc.hh

dune/istl/ildl.hh

dune/istl/ilu.hh

dune/istl/io.hh

dune/istl/matrix.hh

dune/istl/matrixmarket.hh

dune/istl/matrixredistribute.hh