elasticity upscaling - autumn 2013 update

first, this is NOT intended for 2013.10, it cannot go in before dune 2.3 is released.

this is my work on the elasticity upscaling code done this autumn. summary;

- general cleanups
- adjustments for dune 2.3-pre
- add a linear solver capable of handling the ill-conditioned systems involved, thanks to @blattms and dominic kempf!
- add openmp support

since this depends on bleeding edge features it won't even compile with dune 2.2.1.
to compile you have to use dune from git, in particular you have to

1) checkout the p/dominic/umfpack branch in dune-istl
2) merge the feature/twolevel-method branch into it (one conflict, easily resolved).
3) you need a patch i will send to upstream asap.

as this code was done in the opposite order (add openmp, then deal with consequences) and the patch set has been reversed before delivery, there is quite some foreshadowing and things that may seem unmotivated out of context if you try to read it in a linear fashion. 

it passes all sanity checks (compiles at each commit, regression tests pass at each commit). 

the pull request is opened to ease delivery of my work to the employer and for review purposes (no hurry on that obviously).