Merge branch 'cleanup/avoid-warnings' into 'master'

dune/fufem/forms/localfunctionadaptor.hh

dune/fufem/functions/coarsegridfunctionwrapper.hh

dune/fufem/functions/portablepixelmap.hh

dune/fufem/parallel/elementcoloring.hh

dune/fufem/quadraturerules/subentityquadraturerule.hh

dune/fufem/test/dunepythontest.cc

dune/fufem/test/loggertest.cc

dune/fufem/test/test-polyhedral-minimisation.cc

examples/hyperelasticity.cc

examples/minimalsurface-equation.cc

examples/poisson-neumann.cc

examples/poisson-nitsche.cc

examples/primal-plasticity.cc

examples/stokes-taylorhood.cc

examples/utilities.hh