Hacker News Tweaks per holleyp

This extension adds some features to Hacker News (news.ycombinator.com):
- Keyboard navigation.
- Hotkeys for voting, opening links (optionally in new tabs), and page navigation.
- A dark mode toggle at the top right.
- A help button at the top right to show hotkeys and settings, which can be disabled. You can reopen the help/settings menu with Shift+/ even if the button is hidden.
- Un-grays downvoted comments and shows their numeric downvote score. Can be disabled in settings.
- Un-grays post body text (HN makes the body text for text posts grayed out by default).

This is all accomplished in a single .js file and done just with the HTML on the current page (and a couple persistent browser things for remembering your dark mode/graytext settings), making it lightweight compared to other extensions. It is also necessarily source-available since you can just look at the extension itself and see all of the code it uses.