Add library Dune::MetaGrid
This follows a pattern we want to establish in our cmake buildsystem. Every module should have a library even if it does only acts as an interface for dependencies. This MR adds the interface library Dune::MetaGrid.
This follows a pattern we want to establish in our cmake buildsystem. Every module should have a library even if it does only acts as an interface for dependencies. This MR adds the interface library Dune::MetaGrid.