The backend selecting mechanism needs all modules to be imported.
This commit restructures the package to be able to do that. Placement
of some functions felt weird, but this can still be changed.
No more placements in __init__.py anymore though, as this will
result in cyclic dependencies.

It is a memory reinterpretation

Very wild, totally WIP.

Various fixes, including diagonal jacobian transformations.

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

The driver solves the PDE given by the first form in forms. This is a
first step towards instationary problems.

The driver solves the PDE given by the first form in forms. This is a
first step towards instationary problems.