The local copy was to get the thing developed and working.  Now that it is
working we upstream it into dune-grid.

[[Imported from SVN: r9922]]

The IndexSet interface class from dune-grid doesn't have it, and we want
to be like the interface method as much as possible.

[[Imported from SVN: r9921]]

[[Imported from SVN: r9920]]

That's what this method is called in the dune-grid IndexSet
interface.

[[Imported from SVN: r9919]]

[[Imported from SVN: r9918]]

[[Imported from SVN: r9917]]

Yes it is to be moved to dune-grid, but for the transition it is
easier to use the one from this module.

[[Imported from SVN: r9916]]

[[Imported from SVN: r9915]]

[[Imported from SVN: r9914]]

[[Imported from SVN: r9913]]

[[Imported from SVN: r9912]]

That code was written back in the days when we were only using
first order spaces.  Now, with other spaces, we have to properly
distinguish between grid vertices and Lagrange nodes.

[[Imported from SVN: r9911]]

[[Imported from SVN: r9910]]

[[Imported from SVN: r9909]]

Use MPIHelper instead.

[[Imported from SVN: r9908]]

[[Imported from SVN: r9907]]

[[Imported from SVN: r9906]]

[[Imported from SVN: r9905]]

[[Imported from SVN: r9904]]

[[Imported from SVN: r9903]]

[[Imported from SVN: r9902]]

[[Imported from SVN: r9901]]

[[Imported from SVN: r9900]]

[[Imported from SVN: r9899]]

As of yet completely untested

[[Imported from SVN: r9898]]

[[Imported from SVN: r9897]]

The implementation uses TinyXML2.  If you don't have that installed
then a NotImplemented exception will be thrown.

The code is still pretty fragile, and needs more defensive programming.
It will probably crash on a number of well-formed files.

[[Imported from SVN: r9896]]

[[Imported from SVN: r9895]]

[[Imported from SVN: r9894]]

It is not used anymore.  On the other hand, I want to get rid of 
GeometryGrid in the CosseratVTKWriter.  Now with the new VTKFile
at hand there is a chance.

[[Imported from SVN: r9893]]

[[Imported from SVN: r9892]]

[[Imported from SVN: r9891]]

[[Imported from SVN: r9890]]

[[Imported from SVN: r9889]]

[[Imported from SVN: r9888]]

This is needed for projection-based finite elements.

The code in this patch has not been tested yet.

[[Imported from SVN: r9887]]

[[Imported from SVN: r9886]]

dune-solvers actually does provide a way to set these matrices directly.
I simply didn't find it until recently.

[[Imported from SVN: r9885]]

Currently, the only use of FD is to double check the derivatives computed
either by hand-written code or (more frequently) by automatic differentiation.
However, only multiprecision number types allow to really be sure that the
rounding/cut off errors of FD do not hide subtle errors.

Unfortunately, this patch doesn't go all the way.  It now won't run with 'double'
anymore.  Also, user code needs to be modified in small but inelegant ways
(e.g., no 'std::' prefixes for math functions).  Since the FD tests don't
have to be run every day that's okay for now.

[[Imported from SVN: r9884]]

[[Imported from SVN: r9883]]