Disable train waiting notifications

Add option to disable it. I know that some of my trains may be waiting for more than 15 or more than 20 minutes, and I am completely fine with that. I do not need notifications about this.

Maybe offer the option to enable or disable depending where the train is. At a station, I'm happy for it to wait for an hour but in the middle of a line it means a problem.

Technically, when a train is standing in front of an occupied station, it is also standing "in the middle of a line". There is no point in building intermediate stations where the train could stop when it can just wait in line immediately before the station.

IMO this kind of notification is useful only if ALL trains for a certain line are waiting more than 15 minutes. Sometimes demand for coal will be satisfied with a single train every 5 minutes. Other times all 4 trains are not enough. But if all 4 trains are waiting >15 min its more likely the coal mine is borked in some way.