RateLimitedFetcher 网络请求层 — 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/581103/1842602/JM%20Shelf%20-%20Network.js
