[Cleanup] Silence compiler warning about unused typedef
[VariableMonomFEM] Adapt to renamed finite element in dune-localfunctions

The header for the finite element has been renamed to monomial.hh and
the class to MonomialLocalFiniteElement.

Make sure we compile again.
[MonomialFEM] Use Mapper::index() instead of Mapper::map()

This just follows the upstream change in dune-grid.
[Cleanup][Compiler] Remove checks for std::initializer_list

We now require a sufficiently recent compiler to be able to always rely
on std::initializer_list, so drop the preprocessor checks for that
feature.
[testpermutedordering] Check that the ordering works right after construction
[testordering] Use new include for ALUGrid

With the move to dune-alugrid, <dune/grid/alugrid.hh> needs to become
<dune/alugrid/grid.hh>. Note that with this change, the test doesn't
work with the old ALUGrid anymore.
[CMake] Switch to testing for new dune-alugrid module instead of external ALUGRID