Implement Caching for Generic Restriction
Merge Request !308 (merged) implemented generic restriction for Local Finite Elements from dune-localfunctions. The implementation uses a Wrapper to represent all children functions combined as a function on the father domain and afterwards uses standard interpolation from dune-localfunctions.
The relation between parent and children dofs could be cached in a rectangular matrix to save some computation time during the restriction phase (and maybe also prolongation).
Side note: Prolongation is always the standard interpolation of the father function restricted to the child domain.