Wurstmineberg Ultra Softcore 4.0

This release repackages the USC minigame as a Minecraft data pack, removing the MCEdit dependency and vastly simplifying the setup process as a result.

This release targets Minecraft 1.16.

The release is based on the unreleased version 3.9 of the USC box, which is based on version 3.5, since versions 3.6 through 3.8 have unfortunately been lost in the server move from wurstm-hetzner to gharch. Changes made in 3.9 were mostly to make everything work in current versions of Minecraft again.