Feature/add differentiability checks
This MR extends the functionality in dune/functions/functionspacebases/test/basistest.hh
by Checks of strong differentiability.
The code was previously contained in !421 .
This MR extends the functionality in dune/functions/functionspacebases/test/basistest.hh
by Checks of strong differentiability.
The code was previously contained in !421 .