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)

* Enable backend functions which are *not* generators
* Use the sumfac switch as a default switch

Needs a small fix in loopy (MR opened).

It is a memory reinterpretation

... instead of reimplementing it all over the place

That allows us to load that file as a pandas frame.

They are concepts that are not really necessary with local
storage, that I do not really want to explain to other people.

Only register generators globally. This makes inspection of cache
items much easier.

This reverts commit e1bbce4c.