and an example with stokes stress

They are concepts that are not really necessary with local
storage, that I do not really want to explain to other people.

This reverts commit d0a87348.

major remodelling of the DuneTarget

This involves adding a wrapper around the LocalBasisCache, that
has value semantics (at the cost of only allowing indexing with []
into the result and not perform any other operation on it).

Some work on parameter classes, a bugfix on the splitting algorithm
some simplifications in the generation stage

as a consequence introduce template parameters

to dependency extraction
lfs generators
geometry stuff