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/entity/living/EntityDecoy.java

@@ -44,7 +44,7 @@ public class EntityDecoy extends EntitySummonedCreature {
 		if(world.isRemote){
 			for(int i = 0; i < 20; i++){
 				ParticleBuilder.create(Type.DUST)
-				.pos(this.posX + (this.rand.nextDouble() - 0.5) * this.width, this.getEntityBoundingBox().minY
+				.pos(this.posX + (this.rand.nextDouble() - 0.5) * this.width, this.posY
 						+ this.rand.nextDouble() * this.height, this.posZ + (this.rand.nextDouble() - 0.5) * this.width)
 				.time(40)
 				.clr(0.2f, 1.0f, 0.8f)