Merge branch 'feature/remove-facet-box-elembctypes' into 'master'

dumux/multidomain/facet/box/CMakeLists.txt

dumux/multidomain/facet/box/elementboundarytypes.hh

dumux/multidomain/facet/box/properties.hh

test/multidomain/facet/tracer_tracer/CMakeLists.txt

test/multidomain/facet/tracer_tracer/params.input

test/multidomain/facet/tracer_tracer/problem_1p_bulk.hh

...es/test_md_facet_tracertracer_box_onep_bulk-reference.vtu

.../test_md_facet_tracertracer_box_onep_lowdim-reference.vtp

.../test_md_facet_tracertracer_box_tracer_bulk-reference.vtu

...est_md_facet_tracertracer_box_tracer_lowdim-reference.vtp

...s/test_md_facet_tracertracer_mpfa_onep_bulk-reference.vtu

...test_md_facet_tracertracer_mpfa_onep_lowdim-reference.vtp

...test_md_facet_tracertracer_mpfa_tracer_bulk-reference.vtu

...st_md_facet_tracertracer_mpfa_tracer_lowdim-reference.vtp

...s/test_md_facet_tracertracer_tpfa_onep_bulk-reference.vtu

...test_md_facet_tracertracer_tpfa_onep_lowdim-reference.vtp

...test_md_facet_tracertracer_tpfa_tracer_bulk-reference.vtu

...st_md_facet_tracertracer_tpfa_tracer_lowdim-reference.vtp