Enderman attacks a player if he's looking at him.

We still need to check if there is a wall between the player and the enderman, but it works.
They don't attack if he has a pumpkin on his head :)
The total size is 10 degrees, but the maximum difference is still 5 degrees. I'd write `If the player's crosshair is within 5 degrees from the enderman`, is that better?