Added AnvilRepairUpdateEvent

This event fires when two items are placed into the anvil repair GUI.
If the event is left to DEFAULT, vanilla behavior occurs.
If the event is set to ALLOW, the modified event.outputStack will be
applied to the anvil GUI output item.
If the event is set to DENY, then the anvil GUI will not allow the
combination of items.

	new file:   common/net/minecraftforge/event/anvil/AnvilRepairUpdateEvent.java
	modified:   patches/minecraft/net/minecraft/inventory/ContainerRepair.java.patch