multi-body-problem patch to current framework

dune/tectonic/factories/stackedblocksfactory.cc

dune/tectonic/factories/stackedblocksfactory.hh

dune/tectonic/problem-data/grid/mygrids.hh

dune/tectonic/spatial-solving/fixedpointiterator.cc

src/foam/foam.cfg

src/multi-body-problem/CMakeLists.txt

src/multi-body-problem/multi-body-problem-2D.cfg

src/multi-body-problem/multi-body-problem.cc

src/multi-body-problem/multi-body-problem.cfg