Expanded attack definitions

 - Custom mob attacks can now define animation, projectile,
  and interval (cooldown).
 - The syntax is "ItemName@AnimationName@ProjectileName@Interval"
 - ItemName is the name of the attack object.
 - AnimationName is the name of the animation on your custom mob you
  want this attack to use. See `AnimationsGuide.txt` in the zip for a
  list of animations that your base mob can use.
 - ProjectileName is the name of the projectile object.
 - Interval is a delay in seconds before the attack can be used again.
 - For example: "GoblinKing_Beam@attack_bite@dragon_ice_projectile@3"
 - You can leave out sections at the end but you if you want to skip
  a section, you need the @'s still to separate.
 - For example: "GoblinKing_Beam"
 - For example: "GoblinKing_Beam@attack_bite"
 - For example: "GoblinKing_Beam@@dragon_ice_projectile@3"
 - For example: "GoblinKing_Beam@@@3"