Merge branch 'fix/various-compiler-warnings' into 'master'

dumux/assembly/partialreassembler.hh

dumux/geomechanics/elastic/volumevariables.hh

dumux/geomechanics/fvproblem.hh

dumux/geomechanics/poroelastic/volumevariables.hh

dumux/linear/amgparallelhelpers.hh

...x/material/constraintsolvers/compositionfromfugacities.hh

dumux/material/constraintsolvers/ncpflash.hh

dumux/material/spatialparams/fv.hh

dumux/material/spatialparams/fv1p.hh

dumux/material/spatialparams/fvelastic.hh

dumux/material/spatialparams/fvporoelastic.hh

dumux/nonlinear/newtonsolver.hh

dumux/porousmediumflow/1p/volumevariables.hh

dumux/porousmediumflow/2p2c/sequential/fluxdata.hh

test/common/parameters/test_loggingparametertree.cc

test/discretization/box/test_boxfvgeometry.cc

test/discretization/cellcentered/tpfa/test_tpfafvgeometry.cc

...retization/staggered/test_staggered_free_flow_geometry.cc

test/material/components/plotproperties.cc

test/material/fluidsystems/checkfluidsystem.hh