[2.0] A way to add temporary stops without removing a train's group

[MrFastZombie]

With the new groups system players can add temporary stops to a train either through interrupts, or through ctrl clicking on the map in a train's remote view. Both will keep the train's group assigned.

Currently if a lua script tries to add a temporary stop through the method of copying a LuaTrain's schedule, modifying it, and then copying it back to the LuaTrain, it will remove the train's group even if the only real change is a new temporary stop.

What I am requesting is either having the game internally check if a new schedule can be applied without needing to remove the train from a group, or for there to be function to send a train to a station or track as a temporary stop, with optional wait conditions.