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/item/ItemLightningHammer.java

@@ -210,7 +210,7 @@ public class ItemLightningHammer extends Item implements IConjuredItem {
 					if(hit.world.isRemote){
 						ParticleBuilder.create(Type.LIGHTNING).pos(hit.getPositionVector().add(0, hit.height / 2, 0))
 								.target(target).spawn(hit.world);
-						ParticleBuilder.spawnShockParticles(hit.world, target.posX, target.getEntityBoundingBox().minY + target.height / 2, target.posZ);
+						ParticleBuilder.spawnShockParticles(hit.world, target.posX, target.posY + target.height / 2, target.posZ);
 					}
 
 					//target.playSound(WizardrySounds.SPELL_SPARK, 1, 1.5f + 0.4f * world.rand.nextFloat());