Tidy up entity geometry stuff:

- Add a getCentre method for entities to GeometryUtils
- Replace getPositionEyes(0) with getPositionEyes(1) since it's more efficient, and by definition they must be the same
- Remove all the silly getEntityBoundingBox().minY stuff, this bug has been fixed since 1.8! (which begs the question: if it was considered a bug, how on earth did it go unfixed for that long?)
- A few other small things

src/main/java/electroblob/wizardry/misc/Forfeit.java

@@ -190,7 +190,7 @@ public abstract class Forfeit {
 		add(Tier.APPRENTICE, Element.FIRE, create("fireball", (w, p) -> {
 			if(!w.isRemote){
 				EntityMagicFireball fireball = new EntityMagicFireball(w);
-				Vec3d vec = p.getPositionEyes(0).add(p.getLookVec().scale(6));
+				Vec3d vec = p.getPositionEyes(1).add(p.getLookVec().scale(6));
 				fireball.setPosition(vec.x, vec.y, vec.z);
 				fireball.shoot(p.posX, p.posY + p.getEyeHeight(), p.posZ, 1.5f, 1);
 				w.spawnEntity(fireball);