[Dune] DUNE Usage as a 'normal' library

[Christoph Grüninger]

Hi Lukas,

let me add my perspective, too. Dune is super-flexible and remains to be 
very fast. That is achieved by having everything written in C++ without 
much classical object orientation.
If you don't need the flexibility and the last percent of performance, 
you can hard-code everything, you don't need to change, and make other 
parts configurable like boundary conditions or material parameters.
In such a case, you could write a library interface that could be used 
by a GUI.
DuMuX works in a similar manner, but instead of providing a GUI, it uses 
config files that are read in before the simulation is run.

Bye
Christoph