There is way more reasons to interpolate a function into the
solution vector and we cover them with one code path:
* Dirichlet boundary conditions (strong ones)
* Initial conditions for instationary expressions
* Initial guesses for Newton solvers

The visitor state regarding indices needs to be correctly reset
for child iteration in these cases.

These might sound completely silly, but they are useful when writing
code generic w.r.t. the number of components

It has single precision support...

will be superseded by our actual model anyway.

Paper plots

See merge request dominic/dune-perftool!202

We run ut of PIDs during a typical run on KNL.

[cmake] Retrigger code generation from downstream modules

See merge request dominic/dune-perftool!206

So far, changes in the form compiler did not trigger code regeneration
if invoked from a downstream dune module. This is fixed now.

adjust subsamplingvtkwriter to changes in dune-grid 2.6

See merge request dominic/dune-perftool!205

use the backend selector for the jacobian inverse transposed

See merge request dominic/dune-perftool!204

Additionally, uses the right number of subrefined intervals in the blockstructured case