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/spell/LightningPulse.java

@@ -70,7 +70,7 @@ public class LightningPulse extends Spell {
 			}
 			
 			if(world.isRemote){
-				ParticleBuilder.create(Type.LIGHTNING_PULSE).pos(caster.posX, caster.getEntityBoundingBox().minY
+				ParticleBuilder.create(Type.LIGHTNING_PULSE).pos(caster.posX, caster.posY
 						+ GeometryUtils.ANTI_Z_FIGHTING_OFFSET, caster.posZ)
 				.scale(modifiers.get(WizardryItems.blast_upgrade)).spawn(world);
 			}