Added the following to support an optional world whitelist:

• Config options:
  • enabled-worlds (String list)
    • List of worlds where elo tracking is enabled
    • Default: "%all" for all worlds
      
    • Skips list entries that do not match worlds loaded by the server
      • Let me know if the timing of this check conflicts with any multi-world plugins
  • disabled-world-message (boolean)
    • Whether a message is sent to combatants on victim death in a non-tracked world
      
    • Default: false
• Command arguments for /eloa
  • world
    • Gets the next argument and toggles elo tracking for the named world
      
    • Tab-completes based on server's world list
      
    • Fails if internal boolean allEnabled is true, or if world is not found
  • allworlds
    • Toggles internal boolean allEnabled, toggling between server-wide and per-world tracking
  • disabledworldmessage
    • Toggles disabled-world-message

***Plugin download is now served by a self-hosted website to consolidate uploads.***