More updates.

Renamed ReloadHandler.reload() to ReloadHandler.isReloading().
Added custom events and BattlefieldListener.
Renamed FieldListener to MTListener.
Updated TODO list.
Added Infinity enchant to cannons to prevent players from picking up
arrows. Arrows are now subtracted via the PlayerFireEvent listener.
Added DamageHandler and ExplosionHandler for tracking and calculating
damage dealt.