Staggered higher order bug in face solution
The following assertion fails for all freeflow tests after merging !1481 (merged):
/data/src/dumux/dumux/discretization/staggered/facesolution.hh:68: const Dumux::StaggeredFaceSolution::FacePrimaryVariables &Dumux::StaggeredFaceSolution, std::allocator > > >::operator[](IndexType) const [FaceSolutionVector = Dune::BlockVector, std::allocator > >, IndexType = int]: Assertion
pos != map_.end()' failed.`