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/ItemWand.java

@@ -847,7 +847,7 @@ public class ItemWand extends Item implements IWorkbenchItem, ISpellCastingItem,
 
 				if(player.world.isRemote){
 
-					Vec3d origin = new Vec3d(player.posX, player.getEntityBoundingBox().minY + player.getEyeHeight(), player.posZ);
+					Vec3d origin = player.getPositionEyes(1);
 					Vec3d hit = origin.add(player.getLookVec().scale(player.getDistance(event.getTarget())));
 					// Generate two perpendicular vectors in the plane perpendicular to the look vec
 					Vec3d vec1 = player.getLookVec().rotatePitch(90);