Make anisotropic quadrature order possible for non DG examples.

It was the wrong level of asbtraction!

But only when they are actually used!

Conflicts:
	python/dune/perftool/pdelab/quadrature.py

Stage instructions are not the solution.

We previously completely avoided loopy for temporary declaration.
We now rely on it again, but have DuneTemporaryVariable, which is
capable of doing a bit more things (and at the same time handles
the indexing question)

Needs a small fix in loopy (MR opened).

It is a memory reinterpretation

... instead of reimplementing it all over the place