Add first version of the Riemannian Proximal Newton solver, as an alternative to the Trust-Region Solver.

In each step of these two iterative solvers, we try to find a correction
that decreases the energy of the nonlinear functional of the current iterate x.
The correction is calculated using the Taylor expansion around x,
resulting in the problem: Hessian(x) * correction = -gradient(x).
Within a certain radius around x, the functional can be approximated correctly and then
the corrections causes an energy decrease.
1) The trust-region algorithm ensures this using a trust-region.
2) The proximal newton method ensures this by punishing
   large corrections using a regularization factor.

Lisa Julia Nebel authored 5 years ago and Sander, Oliver committed 5 years ago

This class will gradually replace the current implementations
GlobalP1Mapper and GlobalP2Mapper, because dune-gfe is not
the proper place for infrastructure for distributed computing.
Plus, the stuff in dune-parmg already is more flexible and
powerful.

Up until dune-common 2.7, the Dune namespace contained shared_ptr:
First as an actual implementation, later simply as a namespace
import.  Dune-common post-2.7 has removed that import,
and users of shared_ptr really have to explicitly specify
the std:: namespace prefix.

Automatic testing of the RiemannianTrustRegionSolver class requires
to know what it did on the previous run.  This patch adds
some infrastructure to collect this information.

It's the same code, but the old name is deprecated.

This got introduced in dune-grid 2.6.

- use more shared_ptr
- New MCMGMapper interface from dune-grid 2.6
- basis.indexSet() has been removed from dune-functions

A lot of raw pointers have been replaced by std::shared_ptr.

A lot of data members are inaccessible now, and getters have
to be used.

A small patch is still needed for dune-solvers: The iterationStep_
member is still needed to be public, because the new getter only
grants access to the object, not the pointer to it.

This marks the last step of porting the 'cosserat-continuum' application away
from the dune-fufem bases.  One must not(!!!) mix dune-fufem bases with
dune-functions bases, as they use different dof orderings at least in the P2 case.

Patch by Jonathan Youett

[[Imported from SVN: r10056]]

I don't see an elegant way to make this work for a P3 space, even on a single
processor.  Since I need P3 measurements real soon now, I just disable the
entire code.  Not nice.

[[Imported from SVN: r10047]]

This is much cleaner than handing over the Grid only, and then trying
to guess the basis using the preprocessor.  After all, the
RiemannianTrustRegionSolver calls the assembler, so it may know the
function space basis.

[[Imported from SVN: r10035]]

By introducing a factory class that produces GlobalMapper and LocalMapper
types for a given dune-fufem-style function space basis.

[[Imported from SVN: r10034]]

[[Imported from SVN: r9994]]

Because it is not an index, it really is a mapper.

[[Imported from SVN: r9953]]

[[Imported from SVN: r9936]]

In particular this means having to carry mappers for the local indices around.
This makes the code more verbose, but it also makes it easier to see what is
happening.  While coding this stuff I keep having doubts about whether all
the renumbering works correctly...

[[Imported from SVN: r9925]]

The global indexing infrastructure does not currently support P3 spaces.

[[Imported from SVN: r9924]]

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]]

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: r9903]]

[[Imported from SVN: r9878]]

[[Imported from SVN: r9834]]

The hasObstacle_ and obstacles_ fields are now single arrays.
The corresponding fields for the entire grid hierarchy is assembled
within dune-solvers now.

[[Imported from SVN: r9816]]

[[Imported from SVN: r9762]]

[[Imported from SVN: r9727]]

Christian Engwer told me a trick how to get the mpiHelper instance without
known argc and argv.

[[Imported from SVN: r9720]]

[[Imported from SVN: r9708]]

Offer setInitialIterate instead

[[Imported from SVN: r9429]]

[[Imported from SVN: r9428]]

[[Imported from SVN: r8234]]

[[Imported from SVN: r7842]]

[[Imported from SVN: r7837]]

[[Imported from SVN: r7611]]

[[Imported from SVN: r7029]]