train Refuel station rework.

option to only path to a station, if there is a valid station to path to after it. This would keep trains from sitting at fuel stations waiting for a destination station. (alternative would be a rework of how fuel stations work, where they are not in the route, but instead trains just automatically divert to the nearest fuel station when their fuel gets below a set threshold, still reserving their original destination. I mean you would probably leave the existing system, just this would be a new configuration option) Cuase trains keep getting stuck at fuel station for me.