and split mini files to avoid reuse of old vtu files!

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

The cache_context functionality helps greatly here.

laplace is again proceeding to code generation