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]]

[[Imported from SVN: r10014]]

Described in:
 Christof Melcher, "Chiral skyrmions in the plane", Proc. of the Royal Society, online DOI DOI: 10.1098/rspa.2014.0394

[[Imported from SVN: r9996]]