Added Object::resizeGLObjectBuffers(uint) method to help improve the ability

to change the number of active graphics contexts on the fly during an applications
life.

include/osg/VertexProgram

@@ -221,6 +221,9 @@ class OSG_EXPORT VertexProgram : public StateAttribute
 
         virtual void compileGLObjects(State& state) const { apply(state); }
 
+        /** Resize any per context GLObject buffers to specified size. */
+        virtual void resizeGLObjectBuffers(unsigned int maxSize);
+
         /** Release any OpenGL objects in specified graphics context if State
           * object is passed, otherwise release OpenGL objexts for all graphics contexts if
           * State object pointer is NULL.