[2.0.73] on_train_schedule_changed is triggered when schedule entry is dragged but not changed

[BurninSun]

If a train's schedule entry is dragged without actually changing the schedule, on_train_schedule_changed event gets fired. Dragging can be as little as one pixel during a misclick.

Minor issue, but I'd expect the event to only be fired when something in the schedule actually changes.

[Rseding91]

Thanks for the report. While I don't consider this a bug in that it's not breaking anything or causing performance issues - it's simple enough to not send the event in this case. So, I'll change it to work like that for 2.1.