[Feature Request] Store previously played map in a file instead of memory

[Xiaminou]

I have to restart my server often and every time I do it "forgets" what map were previously played and people end up with the same maps they played recently.
I was told it's because UMC stores previously played maps in memory instead of a file.
If that's the case it should be changed to store them in a file so it doesn't reset whenever you restart your server.