Gravitrax speed split (from scratch)

Split version of thing 6819855 ("Remixed" link) so that when a marble is fast enough, it goes straight. However, if a marble is not fast enough, then it goes into one of the two exits on the slow side.

Note: The license is still a Creative Commons - Attribution license because I still made it 100% from scratch, even though it's a remix of one of my things that is also 100% made from scratch.