Merge branch 'fix/old-staggered-fluxes' into 'master'

CHANGELOG.md

dumux/flux/staggered/freeflow/fickslaw.hh

dumux/freeflow/compositional/staggered/fluxvariables.hh

dumux/freeflow/compositional/staggered/localresidual.hh

dumux/freeflow/nonisothermal/localresidual.hh

test/freeflow/ransnc/CMakeLists.txt

...multidomain/boundary/stokesdarcy/1p2c_2p2c/CMakeLists.txt

...references/test_ff_rans2c_kepsilon_twolayer-reference.vtu

test/references/test_ff_rans2cni_komega-reference.vtu

test/references/test_ff_rans2cni_lowrekepsilon-reference.vtu

...ferences/test_ff_stokes2c_densitydrivenflow-reference.vtu

...ndary_darcy1p2c_stokes1p2c_horizontal_darcy-reference.vtu

...dary_darcy1p2c_stokes1p2c_horizontal_stokes-reference.vtu

...y_darcy2p2cni_stokes1p2cni_horizontal_darcy-reference.vtu

..._darcy2p2cni_stokes1p2cni_horizontal_stokes-reference.vtu