Operating Train with extending Route, an Undo should Undo entire Route with one Click

[Krazick]

When the Undo Button on Corporation Frame is selected after Operating a Train, should Undo the entire chain of a single Train Route, rather then just the last one (ie. These Actions should be chained to Previous Actions)

[Krazick]

1. When Confirm Route is selected, walk through all Extend Route Actions backwards to the Start Route
2. Reuse Route is selected, set state that allows Extend Route Action to add to the Route
3. Have an effective "Reverse Route" that swaps the sequence of Route Steps
4. When in the Select Route Mode, Selecting a Map Cell to extend the Route, test if the extend route allows for the next going from the End of the Route, but also test if the route can be extend from the beginning of the Route. If it allows both, extend first from the end, a second click will swap to extend from the beginning (just like the swap to the alternate route if available).