Which changed the interfacing between Python and CMake.

I have the use case of a boundary condition file, whose changes should retrigger
the code generation process.

Also allow the usage of the __static section (as known from dune-testtools).
However, variation in the static section is not yet considered!

Instationary stuff not fixed so far.

The previous test timeout of 20s seems to be insufficient sometimes.  Raise it
to 60s.

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