Separate Nether and The End worlds

[CrazyCloudCraft]

Is your feature request related to a problem? Please describe.
I use this plugin for my survival server and i love it becouse every player can explore his own world. However the Nether and End worlds are the same for all players. So when a player joins the nether it may be that everything is already looted by other players and the dragon has already been slain in the End.

Describe the solution you'd like
It would be nice to create a unique Nether or End world for each player when he/she enters a portal. When the player leaves the world it can be unloaded again so it won't have much impact on the server performance.

Describe alternatives you've considered
Another possible solution for this could be to do this is with the API? Is it possible to create multiple worlds for one player?

It would be nice to have this feature for survival servers :)

Suggested by: @jensuenk