Singleplayer migration

[Proxima]

Slipping: exactly as intended.
Slipping Again: close enough that I wouldn't call it a backroute. However, the floater needs to be removed to prevent a separate backroute, and I forgot to do that on this copy

[Proxima]

Solution to 3-jumper Elixir.

[Proxima]

Solution to Buy One, Get One Free (Part 2).

[Proxima]

Vicious: Simon shared his list of 20 levels missing replays. I already have replays for 11 on the list.