Merge branch 'fix/make-headercheck' into 'master'

dumux/discretization/box/effectivestresslaw.hh

dumux/discretization/box/hookeslaw.hh

dumux/discretization/fvgridvariables.hh

dumux/geomechanics/elastic/localresidual.hh

dumux/geomechanics/elastic/volumevariables.hh

dumux/geomechanics/velocityoutput.hh

dumux/io/vtkfunction.hh

dumux/material/fluidsystems/steamn2cao2h2.hh

dumux/material/spatialparams/fvelastic.hh

dumux/material/spatialparams/fvporoelastic.hh

dumux/porousmediumflow/2p1c/volumevariables.hh

dumux/porousmediumflow/boxdfm/subcontrolvolume.hh

dumux/porousmediumflow/co2/volumevariables.hh

dumux/porousmediumflow/nonequilibrium/volumevariables.hh

dumux/porousmediumflow/richardsnc/volumevariables.hh

dumux/porousmediumflow/tracer/volumevariables.hh

test/material/solidsystems/checksolidsystem.hh

test/porousmediumflow/1p/implicit/1pnispatialparams.hh

test/porousmediumflow/1p/implicit/1ptestspatialparams.hh

...orousmediumflow/1p/implicit/compressible/spatialparams.hh