[playground.spaces.dg.pdelab] fix copy failure, refs #25

dune/gdt/playground/spaces/dg/pdelab.hh

@@ -146,7 +146,7 @@ public:
   PdelabBased(GridViewType gV)
     : grid_view_(gV)
     , fe_map_()
-    , backend_(const_cast<GridViewType&>(grid_view_), fe_map_)
+    , backend_(grid_view_, fe_map_)
     , mapper_(backend_)
     , communicator_(CommunicationChooser<GridViewImp>::create(grid_view_))
     , communicator_prepared_(false)
@@ -159,9 +159,9 @@ public:
    */
   PdelabBased(const ThisType& other)
     : grid_view_(other.grid_view_)
-    , fe_map_(other.fe_map_)
-    , backend_(other.backend_)
-    , mapper_(other.mapper_)
+    , fe_map_()
+    , backend_(grid_view_, fe_map_)
+    , mapper_(backend_)
     , communicator_(CommunicationChooser<GridViewImp>::create(grid_view_))
     , communicator_prepared_(false)
   {
@@ -225,7 +225,7 @@ public:
   } // ... communicator(...)
 
 private:
-  const GridViewType grid_view_;
+  GridViewType grid_view_;
   const FEMapType fe_map_;
   const BackendType backend_;
   const MapperType mapper_;