localStorage + GM storage + 多账号隔离 — JM Shelf 推荐脚本的模块库，通过 @require 被主脚本引用。
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.sleazyfork.org/scripts/581102/1842601/JM%20Shelf%20-%20Storage.js
