This is currently the faster solver

This is where they actually belong, create an own file for identity-dirichlet-values;
before we 'abused' a copy of the file cantilever-dirichlet-values.py

Good to measure whether there is locking, and whether the code works
at all.

So far: 2d only

This will be used in the paper with Hanne, Philipp and Markus
on projection-based FE.