Added Cooldown start, end and state change (start and end) listerer events.

Fixed a bug in the decreaseBy cooldown method.
Added a buff end event.
Fixed a bug where ActiveAbility.getCooldown() would always return null;
Fixed a bug where multiple stat changes at the current maximum time would cause all but the first to be ignored.
Added a StatMod.Info class to allow easier batch creation of stat mods.
Added Sword of the Divine abilities.
Minor tweaks. Max combat time upped to two minutes, comments adjusted.