Tree style comments UI

[JohannesNakayama]

• [x] logged in vs. not logged in
• [x] light / dark mode
• [x] parent thread
  • [x] only one line
  • [x] line color consistent with replies
• [x] vote states
• [x] needs vote badge points to critical comment
• [x] adjust admin features (delete button right)
• [x] show informed upvote ratio between vote buttons