Add Support For Slime World Manager

[CrazyCloudCraft]

Is your feature request related to a problem? Please describe.
I think this feature will be good for some minigames or modes like skyblock where each player can have his own world with his island and this world created with SWG is good for owners because uses less space disk and load faster and much more:).

Describe the solution you'd like
Hook SWM so you can also create worlds with slime format.
Describe alternatives you've considered
SWM: https://github.com/Grinderwolf/Slime-World-Manager

Additional Info
"Note that SWM is not intended to be used on big survival worlds, but small worlds like minigame maps or server lobbies. There's more on this on the FAQ section." So as i say this is good for minigames worlds or per player islands worlds for skyblock.

Suggested by: @FunkyNico