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/Node

@@ -299,6 +299,8 @@ class OSG_EXPORT Node : public Object
         /** Get the const compute bound callback.*/
         const ComputeBoundingSphereCallback* getComputeBoundingSphereCallback() const { return _computeBoundCallback.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