Allow plugins to enchant already enchanted items. Fixes BUKKIT-1956

This causes the server to generate PrepareItemEnchantEvent even in the
case that an item is already enchanted or otherwise would normally not
be enchantable.
Add missing semicolon

I should try to compile before I say "this change is okay".
I should try to compile before I say "this change is okay".
I should try to compile before I say "this change is okay".
I should try to compile before I say "this change is okay".
for i in range(100)
Improve calling of ProjectileHitEvent. Fixes BUKKIT-3872
Correct missed diff on skeletons. Fixes BUKKIT-3912
Properly copy collection references in ItemMeta.clone(). Fixes BUKKIT-3913

When cloning an item, all references are copied to the new item. For
collections, this makes internal changes become visible in both the old and
new items.

In CraftMetaItem, clone was not making copies of the appropriate collections
and has been fixed for non-null values.

In CraftMetaEnchantedBook and CraftMetaPotion, clone was using possible empty
collection references and has been changed to explicitly null-check instead.
Call appropriate event for zombies igniting players. Adds BUKKIT-3915
Call PotionSplashEvent even for no effects. Fixes BUKKIT-3618

When a splash potion has no applicable effects we currently do not call
PotionSplashEvent. This means plugins are unable to make custom
potions with reliable splash handling as they have to relicate the
functionality themselves.

With this commit we simply make the event fire regardless of the effects
on the potion.
Remove relocation
Upgrade maven