You don't need this unless you're planning on writing a script that runs alongside Replay Rewrite.
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.greatest.deepsurf.us/scripts/418636/880565/libpbr21.js
this is the original library by pabst, used by many of his scripts.
I'm merely trying to make it usable today by loading it in https versions of pages and making minor changes.
