Merge branch 'feature/remove-deprecated-features' into 'master'

CHANGELOG.md

dune/istl/CMakeLists.txt

dune/istl/colcompmatrix.hh

dune/istl/ilu.hh

dune/istl/istlexception.hh

dune/istl/owneroverlapcopy.hh

dune/istl/paamg/construction.hh

dune/istl/paamg/pinfo.hh

dune/istl/paamg/test/amgtest.cc

dune/istl/paamg/test/anisotropic.hh

dune/istl/paamg/test/fastamg.cc

dune/istl/paamg/test/galerkintest.cc

dune/istl/paamg/test/hierarchytest.cc

dune/istl/paamg/test/kamgtest.cc

dune/istl/paamg/test/pamgmmtest.cc

dune/istl/paamg/test/pthreadamgtest.cc

dune/istl/paamg/test/pthreadtwoleveltest.cc

dune/istl/paamg/test/twolevelmethodtest.cc

dune/istl/solvers.hh

dune/istl/test/foreachtest.cc