Fix underground train recording

[sobri909]

Before I open sourced LocoKit, Arc App had a dirty hack that made the underground train recording about as perfect as possible. It consistently got better results than Moves or anything else.

Then when I was open sourcing LocoKit, I saw that dirty hack, and thought "eh? what's this shit? what does that even do? that's not staying", and I ripped it out.

Oops.

So yeah, I need to spend a day on this. That's probably all it'll take. Find the old dirty hack in the private repo's history, put it back into LocoKit, then go spend a few hours on underground trains, making sure it's all good again.