Throw out the AmiraMesh support instead.  I have not seen
anybody using Amira for years.

It combined computing rod configurations and their discretization
errors.  Nowadays the way to do that is to use rod3d.cc for the
rod configurations, and compute-disc-errors.cc for the errors.
Hence rod-eoc.cc is not needed anymore and can go.

Previously, the layout of my computer's file system was
hard-coded here.

In this file they are not needed at all anymore.

It does not look like that code is used anytime soon, so let's get rid
of it for the sake of tidyness.

Added program to solve a combined minimization problem:
Minmize the sum of an elastic energy (representing the substrate)
and a cosserat energy (representing a thin film on the substrate).

These two files are very similar, and merging them will reduce
maintenance effort in the future.  As of this patch, there is
now quite a number of preprocessor directives in the new merged
cosserat-continuum.cc.  That is not pretty, but the new state
is still much easier to maintain than two completely separate
files.  What is more, I hope to be able to reduce some of that
preprocessor trickery by smarter use of the dune-functions
basis trees.

This used to work only with dune-fufem bases, but the method
constructBoundaryDofs recently learned to also handle the bases
of dune-functions.

This used to be a yes/no, parameter, now we require 'cube'
rather that 'yes' or 'true'.

The original implementation measured the error of SO(3)-valued
functions in quaternion space in a few places.  This patch
converts another occurrence of this to matrix space.

That way, we can use 'if constexpr', and get suitable
writing methods for all kinds of TargetSpace, without
ugly preprocessor tricks.

'Only' a stupid typo: '=' instead of '+='.

As of version 2.6, dune-functions doesn't properly do interpolation
of vector-valued functions with scalar-valued bases anymore.

The code it contains is adolcnamespaceinjections.hh.

In this case, two different refinements of the grids are not
necessarily geometrically identical.  This means we cannot
use hierarchic search with the global position of a quadrature
point, and expect to find the point on the other grid as well.

Instead, we go done to the coarsest grid, and make the transfer
to the other grid there.

Capturing any polymorphic object by value is wrong,
and gcc 8 started to warn about this in the case
of exceptions.

The latter is deprecated as of dune-functions 2.6.

This is needed to build with a recent dune-common and dune-fufem

Previously, the error norms where computed in the respective global
embedding space of the TargetSpace.  For the case of Rotation<3>
this was the space of quaternions, because this is how the
Rotation class is implemented.  However, this does not lead to
correct results.  Therefore, this patch adds special handling
for Rotation<3>, and computes the errors norms in the space of
3x3 matrices.