Mark owned ScummVM Games

This script adds on-hover toggle buttons which allow you to grey out games in the ScummVM compatibility list which you already own to get a clean view of what you still have to keep an eye out for.

It stores your data within the userscript's private store via GM_setValue, so you shouldn't need to worry about your owned/unowned statuses being erased by things like clearing cookies.

It is only tested on Greasemonkey but there's no obvious reason it shouldn't also work under Tampermonkey.