Fix the use of projection-based finite elements in cosserat-continuum

See merge request !78

Add multiplication of a ScaledIdentityMatrix with another FieldMatrix to the collection in linearalgebra.hh

Cosserat-Continuum-Nonplanar

See merge request !72

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

Fix/pipeline

See merge request !76

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.