code: public static Xml exports(LayerableConfig config)
      {
          Check.notNull(config);
  
          final Xml node = new Xml(NODE_LAYERABLE);
          node.writeInteger(ATT_REFRESH, config.getLayerRefresh());
          node.writeInteger(ATT_DISPLAY, config.getLayerDisplay());
  
          return node;
      }
docs: Exports the layerable node from config.
  
  @param config The config reference (must not be <code>null</code>).
  @return The layerable node.
  @throws LionEngineException If unable to read node or invalid integer.