move containers into a separate directory

configure.ac

dune/common/Makefile.am

dune/common/container/.gitignore

dune/common/container/Makefile.am

dune/common/container/array.hh

dune/common/container/arraylist.hh

dune/common/container/bitsetvector.hh

dune/common/container/sllist.hh

dune/common/container/test/.gitignore

dune/common/container/test/Makefile.am

dune/common/container/test/arraylisttest.cc

dune/common/container/test/arraytest.cc

dune/common/container/test/bitsetvectortest.cc

dune/common/container/test/sllisttest.cc

dune/common/fvector.hh

dune/common/parallel/indexset.hh

dune/common/parallel/indicessyncer.hh

dune/common/parallel/remoteindices.hh

dune/common/parallel/test/syncertest.cc

dune/common/parametertree.hh