Because it really is only an energy.

Because it is not a stiffness, it is really just an energy.

Previously, they all inherited from LocalGeodesicFEStiffness,
which was weird, because none of them implemented first or
second derivatives as you would expect from something called
'stiffness'.

The main reason for this is that it is apparently needed for situations
where the grid dimension is not the world dimension.  It is a bit
shorter two.  I was hoping that it would also be faster, because we
eliminate an intermediate matrix object.  However, preliminary tests
have not shown any differences.

The new value is what you need for linear target spaces.
I am not convinced that this is sufficient, but it matches
what we do for simplices.

The whole quadrature business will need some theoretical
investigations eventually.

Make them a parameter instead.  This allows to switch more easily between
geodesic finite elements and projected finite elements.

This is how the new dune-functions bases should be used.  Also, it is yet
another step towards merging CosseratEnergyLocalStiffness and MixedCosseratEnergy.

Conceptually cleaner, and makes for simpler code.  Most importantly, we will want
to pass the Basis::LocalView to the local assemblers.  For that we need the actual
basis, not just the grid view and local finite element.

[[Imported from SVN: r10082]]

... so much difficult code obsolete now... AD rocks...

[[Imported from SVN: r10010]]

[[Imported from SVN: r9379]]

[[Imported from SVN: r9307]]

Because nowadays, it may not be a FieldMatrix anymore

[[Imported from SVN: r9305]]

[[Imported from SVN: r9302]]

[[Imported from SVN: r9301]]

[[Imported from SVN: r8242]]

[[Imported from SVN: r8182]]

Computation of analytical energy gradients doesn't work, yet.

[[Imported from SVN: r7839]]

[[Imported from SVN: r7837]]

[[Imported from SVN: r7617]]

[[Imported from SVN: r7611]]

[[Imported from SVN: r7553]]

[[Imported from SVN: r7416]]

using a finite-difference approximation only for the derivative
of the gfe gradients wrt coefficients.

[[Imported from SVN: r7230]]

[[Imported from SVN: r7228]]

[[Imported from SVN: r7227]]

[[Imported from SVN: r7131]]

[[Imported from SVN: r7030]]

[[Imported from SVN: r7024]]

transpose one gradient matrix.  This makes the code run, but it still doesn't work even for RealTuple<1>

[[Imported from SVN: r6547]]

[[Imported from SVN: r6500]]

[[Imported from SVN: r6498]]

übersetzt jetzt und stürzt nicht ab.  Es kommt allerdings noch Unfug raus.

[[Imported from SVN: r6451]]

[[Imported from SVN: r6297]]

[[Imported from SVN: r5931]]

[[Imported from SVN: r5807]]

[[Imported from SVN: r5741]]

[[Imported from SVN: r5594]]