Moves code for keeping track of players to DropperArenaPlayerRegistry
Adds a DropperArenaRecordsRegistry for keeping track of records
Stores playing players as DropperArenaSession to be able to store more metadata
Adds an enum for different arena game-modes
Adds a record result enum for defining which kind of record a player achieved (personal or global)
Adds a helper-class for teleporting a player to and from arenas