Instationary stuff not fixed so far.

The previous name was *really* confusing.

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

- Use TensorProductElement in one example.

- We still use the sumfact option to swicth to the sum factorization
  code branch. This way it is still possible to easily swicth between
  sumfact and non sumfact code.

- Only TensorProductElements with the same degree in all directions
  will work. Anisotropie and adaption of quadrature rule will happen
  in the next commits.

Do not annotate FiniteElements anymore, further split driver code

Conflicts:
	python/dune/perftool/pdelab/driver/taskbased.py

We never really used or trusted it.

Do not annotate FiniteElements anymore, further split driver code

Conflicts:
	python/dune/perftool/pdelab/driver/taskbased.py