the method index now returns an lvalue

[[Imported from SVN: r1781]]

grid/uggrid/ugfunctions.hh

@@ -233,17 +233,27 @@ namespace Dune {
     }
 
     //! Gets the index of a UG element
-    static int index(const typename TargetType<0,dim>::T* theElement) {
+    static int& index(typename TargetType<0,dim>::T* theElement) {
       return theElement->ge.id;
     }
 
+    //! Gets the index of a UG element
+    static const int& index(const typename TargetType<0,dim>::T* theElement) {
+      return theElement->ge.id;
+    }
+
+    //! Gets the index of a UG node
+    static int& index(typename TargetType<dim,dim>::T* theNode) {
+      return theNode->id;
+    }
+
     //! Gets the index of a UG node
-    static int index(const typename TargetType<dim,dim>::T* theNode) {
+    static const int& index(const typename TargetType<dim,dim>::T* theNode) {
       return theNode->id;
     }
 
     //! Calm the compiler
-    static int index(const void* theWhatever) {
+    static int& index(const void* theWhatever) {
       DUNE_THROW(NotImplemented, "No index available for this kind of object");
       return 0;
     }