Merge branch 'feature/introduce-model-traits' into 'master'

dumux/assembly/boxlocalassembler.hh

dumux/assembly/cclocalassembler.hh

dumux/assembly/staggeredlocalassembler.hh

dumux/common/properties.hh

dumux/common/properties/model.hh

dumux/common/staggeredfvproblem.hh

dumux/discretization/box/fickslaw.hh

dumux/discretization/box/fourierslaw.hh

dumux/discretization/box/fourierslawnonequilibrium.hh

dumux/discretization/box/maxwellstefanslaw.hh

dumux/discretization/cellcentered/mpfa/darcyslaw.hh

...retization/cellcentered/mpfa/elementfluxvariablescache.hh

dumux/discretization/cellcentered/mpfa/fickslaw.hh

...cretization/cellcentered/mpfa/fluxvariablescachefiller.hh

...iscretization/cellcentered/mpfa/gridfluxvariablescache.hh

dumux/discretization/cellcentered/tpfa/fickslaw.hh

...cretization/cellcentered/tpfa/fluxvariablescachefiller.hh

dumux/discretization/cellcentered/tpfa/maxwellstefanslaw.hh

dumux/discretization/fvproperties.hh

dumux/discretization/staggered/freeflow/fickslaw.hh