Merge branch 'feature/maybe_unused-replace-DUNE_UNUSED' into 'master'

CHANGELOG.md

dune/common/alignedallocator.hh

dune/common/debugallocator.hh

dune/common/densematrix.hh

dune/common/diagonalmatrix.hh

dune/common/enumset.hh

dune/common/fmatrix.hh

dune/common/fmatrixev.cc

dune/common/fvector.hh

dune/common/hybridutilities.hh

dune/common/lru.hh

dune/common/mallocallocator.hh

dune/common/parallel/communication.hh

dune/common/parallel/communicator.hh

dune/common/parallel/indexset.hh

dune/common/parallel/indicessyncer.hh

dune/common/parallel/remoteindices.hh

dune/common/parallel/test/remoteindicestest.cc

dune/common/parallel/test/syncertest.cc

dune/common/parallel/test/variablesizecommunicatortest.cc