Ender facing event and render item as bow hook

This PR adds a hook for items which should render as bows in the 3rd
person view without needing a fancy custom ItemRenderer.
Also it adds an event for when the player looks at an Enderman. It is
cancellable if you want to prevent the Enderman going aggro when looked
at.
"Why not an item hook?" Because the event allows people to do more stuff
like "has the player a certain item in his inventory", "does the player
/ Enderman stand on a certain block", "does the Enderman hold a certain
block in his hands" etc. For my purposes it would check if a player
wears a full set of certain armor.