Trains doesn't auto-turn on reverse

# Describe the bug
If i reverse a train (or any other rail-using vehicle), the auto-turn doesn't activate and makes the train derailed.

# Steps To Reproduce
1. Get inside a subway
2. Spawn one of the trams
3. Get on the train
4. Go reverse on the train
5. Try hitting the corner

# Expected behavior
The train auto-turn when it meets a corner, even reversed

# Screenshots
Before reversing
After reversing

# Versions and configuration
- OS: Windows [64-bit]
- Game Version: 0.D-3178-g258b2e8
- Graphics Version: Tiles
- Mods loaded: [
Dark Days Ahead [dda],
Disable NPC Needs [no_npc_food]
]

# Additional context
Save for easier testing:
[Chatom.zip](https://github.com/CleverRaven/Cataclysm-DDA/files/3194741/Chatom.zip)

Use the linked Chatom.zip save and follow the five reproduction steps, reversing a tram into a corner. Trace the rail vehicle behavior at the corner and compare forward and reverse movement; done means auto-turn activates while reversing and the vehicle does not derail.

Written by the indexing model from the issue text.