Merge branch 'feature/staggered-components' into 'next'

dumux/discretization/fickslaw.hh

dumux/discretization/staggered/freeflow/fickslaw.hh

dumux/discretization/staggered/globalvolumevariables.hh

dumux/freeflow/CMakeLists.txt

dumux/freeflow/staggered/fluxvariables.hh

dumux/freeflow/staggered/localresidual.hh

dumux/freeflow/staggerednc/CMakeLists.txt

dumux/freeflow/staggerednc/fluxvariables.hh

dumux/freeflow/staggerednc/indices.hh

dumux/freeflow/staggerednc/localresidual.hh

dumux/freeflow/staggerednc/model.hh

dumux/freeflow/staggerednc/properties.hh

dumux/freeflow/staggerednc/propertydefaults.hh

dumux/freeflow/staggerednc/volumevariables.hh

dumux/freeflow/stokesnc/localresidual.hh

dumux/implicit/staggered/localjacobian.hh

dumux/implicit/staggered/newtoncontroller.hh

test/freeflow/CMakeLists.txt

test/freeflow/staggered/channeltestproblem.hh

test/freeflow/staggerednc/CMakeLists.txt