encapsulate UG?d::grid as well

[[Imported from SVN: r1083]]

grid/uggrid/ugtypes.hh

@@ -6,6 +6,7 @@
 namespace UG2d {
   struct multigrid;
   struct domain;
+  struct grid;
 
   union element;
   struct node;
@@ -14,6 +15,7 @@ namespace UG2d {
 namespace UG3d {
   struct multigrid;
   struct domain;
+  struct grid;
 
   union element;
   struct node;
@@ -37,6 +39,8 @@ namespace Dune {
   public:
     typedef UG2d::multigrid MultiGridType;
 
+    typedef UG2d::grid GridType;
+
     typedef UG2d::domain DomainType;
   };
 
@@ -46,6 +50,8 @@ namespace Dune {
   public:
     typedef UG3d::multigrid MultiGridType;
 
+    typedef UG3d::grid GridType;
+
     typedef UG3d::domain DomainType;
   };