It used to be in dune-functions originally, but got moved to
dune-common eventually.  This patch updates the code to reflect
that move.

Otherwise some dune-common stuff will not work properly,
for example copying of FieldMatrices that use adouble
as their number type.

It has been removed from dune-functions in the last release
(at least).

We can now completely control the approximation order by a const int,
which is much nicer.

Because these two classes are for the most part identical.

Currently, this merged version involves some trickery, including some template
specializations and multiple inheritances.  I hope to get rid of that, eventually.

This is an important step towards making the 'mixed' Cosserat code more like
the regular one.  The mid-term goal is to merge the two implementations, because
there is way too much code duplication here.

That really was a hack: the build system should do it.

[[Imported from SVN: r10111]]

[[Imported from SVN: r10103]]

[[Imported from SVN: r10102]]

[[Imported from SVN: r10093]]

[[Imported from SVN: r10085]]

[[Imported from SVN: r9997]]

[[Imported from SVN: r9860]]

'Mixed' means that the spaces for deformations and microrotations can
be chosen separately.

At this point there hasn't been a lot of testing yet.  In particular,
parallelizing the assembly is currently not supported.

[[Imported from SVN: r9852]]

[[Imported from SVN: r9829]]

That makes it easier to keep them consistent.  Also, the code is shorter.

[[Imported from SVN: r9822]]

[[Imported from SVN: r9821]]

[[Imported from SVN: r9820]]

This used to be 'int', because dunepython didn't support the python-to-C
conversion for bool.

[[Imported from SVN: r9819]]

In particular, I can use math.cos in the initial values.

[[Imported from SVN: r9808]]

[[Imported from SVN: r9803]]

[[Imported from SVN: r9802]]

Newer versions of ADOL-C do not define 'overwrite' anymore, hence there
is no risk of macro clashing.

[[Imported from SVN: r9798]]

[[Imported from SVN: r9797]]

[[Imported from SVN: r9796]]

That way, we can now control what vertices are Dirichlet and Neumann without having
to recompile the code.

[[Imported from SVN: r9794]]

This will eventually allow to not hard-wired the Dirichlet vertices
into the C++ code, and change them without recompiling.  This also
means we can remove some preprocessor switches.

Currently, though, the Python code is still hard-wired, so we are
only half-way there.

Note that this patch may break several test problems.  I did not test
all of them.

[[Imported from SVN: r9793]]

[[Imported from SVN: r9789]]

[[Imported from SVN: r9787]]

[[Imported from SVN: r9780]]

[[Imported from SVN: r9775]]