Established basic gameplay.

Changelog
+ Spawn and portal locations can now be centered
+ Optional waiting room functionality for arenas was added
+ Friendly fire protection between monsters has been added
+ Players logging out in an active arena will now return to the lobby upon rejoining
+ Arena settings can no longer be changed while it is open
+ Closing an arena now kicks all players playing in the arena

* Mobs now spawn with random delay in between and with random armor/weapons based on difficulty (basically wave number)
* Shop generation is now completely randomized for material and enchants according to shop level (every 10 waves)
* Armor bought in shops will now automatically equip if possible
* A lobby is now required to open an arena
* All plugin notifications now precede with "VD:"
* Updated admin GUI for upcoming functionalities
* Color rebalancing and rewording for consistency across the board
* Many bug fixes
* Updated configs and data file structures to reflect changes