Fixed constness of EntityRange begin() and end() methods.

git-svn-id: http://www.openmesh.org/svnrepo/OpenMesh/trunk@1182 fdac6126-5c0c-442c-9429-916003d36597

src/OpenMesh/Core/Mesh/PolyConnectivity.hh

@@ -594,8 +594,8 @@ public:
   class EntityRange {
       public:
           EntityRange(CONTAINER_TYPE &container) : container_(container) {}
-          ITER_TYPE begin() { return (container_.*begin_fn)(); }
-          ITER_TYPE end() { return (container_.*end_fn)(); }
+          ITER_TYPE begin() const { return (container_.*begin_fn)(); }
+          ITER_TYPE end() const { return (container_.*end_fn)(); }
 
       private:
           CONTAINER_TYPE &container_;