Attempt to implement checksums for games bought on GOG

Problem:

According to the community wishlist, there are over 1000 people who want to see this feature:
https://www.gog.com/wishlist/site/my_account_provide_checksums_eg_md5_sha1_etc_for_downloadable_files

Sadly, the guys at GOG don't seem to care, although it wouldn't be hard to add that feature.

Solution:

There have been smart people already who made an unoffical documentation of APIs used by GOG:
https://gogapidocs.readthedocs.io

Turns out that there are so called "chunklists" that are a part of the GOG Galaxy client.
These XML files contain metadata for installers. And actually, there are MD5 hashes in there!
They just never get shown to users at any point.

My userscript tries to use these APIs and show these hashes right below the download links.
Also I managed to show the date when the installer was uploaded or last updated.

Preview:

Disclaimer:

I cannot guarantee that there will be any updates for this script. It may contain bugs and
things will probably break when the GOG game library website receives updates.

Please feel free to copy this userscript, improve it and keep it alive.