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/Object

@@ -118,6 +118,8 @@ class OSG_EXPORT Object : public Referenced
         /** Get const user data.*/
         inline const Referenced* getUserData() const { return _userData.get(); }
 
+        /** Resize any per context GLObject buffers to specified size. */
+        virtual void resizeGLObjectBuffers(unsigned int /*maxSize*/) {}
 
         /** If State is non-zero, this function releases any associated OpenGL objects for
            * the specified graphics context. Otherwise, releases OpenGL objexts