render item as bow and Enderman Facing Event

This PR adds a hook for items, where an item should be held as bow
without fancy custom ItemRenderers.
The second thing in this PR is an event for the Enderman. It will
trigger if the player looks at an Enderman. You can cancel it if you
don't want to make the Enderman aggro.
"Why not making an item hook for it?" Because the purpose I see is I
need an event to check if a player wears a complete set of armor, not
just the helmet (like the pumpkin). Also you can completely deactivate
the "make enderman aggro when facing" feature without any items.