Dark Mode, now on Desktop

Yah know, usually we'd come up with a really great feature release writeup touting this as a win for the internet et al. but to be honest with you I just needed to release some other stuff and didn't want to have to cherry-pick commits. So here we are, with a somewhat complete version of dark mode ready to divide you further between the all-black purists and the "can you make a hi-vis orange theme for when I'm browsing in a crosswalk?" weirdos that we know and love. So go forth gentle digglers and digglettes into that dark mode horizon, free from blue-light and red-dit.