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/Fangs.java

@@ -41,7 +41,7 @@ public class Fangs extends Spell {
 
 	@Override
 	public boolean cast(World world, EntityPlayer caster, EnumHand hand, int ticksInUse, SpellModifiers modifiers){
-		if(!spawnFangs(world, new Vec3d(caster.posX, caster.getEntityBoundingBox().minY, caster.posZ),
+		if(!spawnFangs(world, caster.getPositionVector(),
 				GeometryUtils.replaceComponent(caster.getLookVec(), Axis.Y, 0).normalize(), caster, modifiers)) return false;
 		this.playSound(world, caster, ticksInUse, -1, modifiers);
 		return true;