Change the keywords for switching between the solvers to trustRegion and proximalNewton also in film-on-substrate

Now all combinations of dim = dimworld or dim != dimworld and MIXED_SPACE = 0 or MIXED_SPACE = 1 at least compile.

This has to be dimworld and not dim.

The StressFreeStateGridFunction is the actual parametrization from the grid to the
nonplanar Cosserat shell in stress-free state.
The geometries of the StressFreeStateGridFunction will then be used for all calculations
instead of the linear geometries of the piecewise linear grid.

Also remove dune-cuvedgeometry as it is a dependency of dune-curvedgrid

This has been changed to Dune::Vtk::FormatTypes::ASCII in the dune-vtk module

System test for the Cosserat rod problem

See merge request !75

The previous implementation worked only for first-order finite element
spaces, because it assumed that grid vertices and Lagrange nodes
were identical.

This test assembles and solves a prototype Cosserat problem.
In then checks whether the required number of iterations and the
final energy match given (hard-coded) values.

Feature/stress plot

See merge request !73

Remove support for Dune 2.6 and older

See merge request !74

Small change/fix in Mixed Riemanian Trust region solver

See merge request !69

Modernize rod code

See merge request !67

Otherwise the Cosserat rod code will not compile without dune-parmg.

This reflect the current purpose of the test much better.

So far, the Cosserat rod energy implementation hat a first-order
finite element space hardcoded.  This patch removes that restriction.
As for the other models in this Dune module, the finite element basis
is now a template parameter of the model energy, and can be set to
any reasonable basis.

It is not a 'stiffness' anymore, but really only implements the
energy.

This is a prerequisite to a) support for higher-order FE,
and b) getting rid of the hand-written CosseratVTKWriter.

Previously, the rod3d code used a hand-implemented first derivative
of the rod energy, and FD for the second derivatives.  This patch
replaces this by ADOL-C for both first and second derivatives.
Advantages are:
* The code is much shorter, and easier to understand.
* The previous code contained interpolation formulae for
  first-order 1d geodesic finite elements.  This restricted
  rod problems to first-order GFE.  A follow-up patch will
  allow higher-order approximations.
* The new code runs roughly twice as fast.

GeodesicFEAssembler can replace it without problems.

As a first step towards getting rid of the RodAssembler class,
this patch moves the getStrain, getStress, and getResultantForce
methods to the RodLocalStiffness class.  I am not 100% convinced
that that is the best place for them, but I can't think of a
better one right now.

ADOL-C implements most standard math functions for its
'adouble' type, and they are not in the namespace 'std'.
dune-fufem contains a file adolcnamespaceinjections.hh
which imports some of these methods into the 'std'
namespace, but that is not the proper way to do it.
Rather, they should be found by argument-dependent
lookup (ADL), that is

  using std::sin;
  auto v = sin(x);

fixed mixed riemanniansolver issues

See merge request !68