Because it really is a functionality of rotation matrices in quaternion
representation.  Only the Cosserat energies use it at the moment, but
this is coincidental.

In the same process, the method is renamed to quaternionTangentToMatrixTangent.
That seems to be a more telling name.

In particular, we move the test for the computeDR method from
cosseratenergytest.cc to here.  It is a method that does not
have anything to do with Cosserat mechanics directly.

The test still seems overly complicated.  Do I really need
a LocalGeodesicFEFunction?  Maybe I can simplify it later.