Train stop, alternate version of one, only goes when full.#955

Currently the trains stop, then just go even if they don’t pick anything up. This can be annoying as they sometimes leave the station right after the shapes are ready to be loaded.
Also, if the shapes arrive at different times to be loaded, then the train only picks up 1 or 2 shape blocks.
In my opinion, I would prefer to have a backlog of trains, or at least have the option to, instead of having the trains just go right through the stop.

Coming in 0.1.0