Added damage event.
(Event will only call when the player is using ItemsCore item)
Usage:
core.setOnDamageEvent(core.createRunnable("<code>"))
Special variables:
attacker -> Player who attacked
victim -> Entity that got damaged
cause -> DamageCause of the event
event -> The event itself (you can do event.setCancelled(true) to cancel it like it never happened)
damage -> The amount of damage dealt
item -> Item used to damage