They are only to a lesser extent important for our HPC applications
and the vectorization algorithm struggles with the complexity of the
search space.

So far, we had the opcounter cast to Dune::FieldVector
of size 1. Now it defines the correct type.

Simple test passes already

Avoid explicit doubles.

Avoid explicit doubles.

They are not used in a senseful way anyway and loopy
stumbled over them.

This is currently only used for level 4 instrumentation,
as these start and stop markers were messing heavily with
dependencies in the sum factorization code. This way, the necessary but
ugly work of adding instrumentation is separated much more
nicely.

I was tired of the amount of ifs that changed behaviour
depending on stage 1 or 3. This is a cleaner approach.