Added intialization of the VAO in Geometry::compileGLObjects() and refined the invocation of updates to the VAO

include/osg/VertexArrayState

@@ -88,6 +88,8 @@ public:
             _currentEBO = 0;
         }
 
+        void resetBufferObjectPointers() { _currentVBO = 0; _currentEBO = 0; }
+
         void assignAllDispatchers();
 
         virtual void assignVertexArrayDispatcher();