Save and load collapsed diffs with cookie

I am glad to find this extension! This extension is exactly what I wanted. But currently when we reload the PR page, all collapsed diffs will be expanded.

I've implemented save/load function with cookie. Now even when we reload the page, we can see same state which means collapsed diffs stay collapsed and expanded diffs stay expanded.
I used filename as a key for cookie. Cookie relies on page URL. So only if URL and filename are same, the plugin collapse diff automatically.