Hide Dune::DerivativeLayout in namespace
The 'generic' local finite element implementations
based on the framework in utility/
define an
enum DerivativeLayout {value, derivative}
in the
namespace Dune
. By putting this
into a seperate namespace Dune::DerivativeLayoutNS::
we can avoid cluttering the namespace Dune::
with
Dune::derivative
and Dune::value
.