(instead of having the prototype in loopy)

Requires lots of monkey patches...

Only 6 orders of magnitude to go!

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

Do not use continue stuff. Instead precompute the quantities.

requires an upstream fix

This removes:
- The now obsolete quadrature_loop_statement.
- Quadrature weights are now a globalarg and we do not create a
temporary anymore.

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)