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/Drawable

@@ -278,6 +278,9 @@ class OSG_EXPORT Drawable : public Object
         */
         virtual void compileGLObjects(RenderInfo& renderInfo) const;
 
+        /** Resize any per context GLObject buffers to specified size. */
+        virtual void resizeGLObjectBuffers(unsigned int maxSize);
+
         /** If State is non-zero, this function releases OpenGL objects for
           * the specified graphics context. Otherwise, releases OpenGL objexts
           * for all graphics contexts. */