More Rail Vehicles

[mx-moonling]

Summary

Content "Adds new rails vehicles"

Purpose of change

The current rail vehicles are very large (7x17), and do not coexist well with the rail system we have. They derail frequently and ram into obstacles outside their overmap tile when turning.

Describe the solution

Adds a 7x12 train chassis for spawning and to allow other contributors an easier time building a new train car in the future.
Adds a 7x12 diesel locomotive.
Adds a 7x12 passenger car.
Adds a two more pairs of non steerable rail wheels to the 6 person draisine. Having some non steerable wheels seems to make it behave better.

I decided on a 7x12 layout because it allows for two passenger cars to be placed per map tile, and while still feeling very big and train sized, works well on the railroads.

Describe alternatives you've considered

Bringing the wheels on existing closer towards the center of the train. This allows the locomotive and passenger car to take turns, but leads to having a very large overhang on either side, which smash into many obstacles even above ground, and seem weird.
Finding a way to expand the zone cleared out by subway and railroad generation.

Testing

Made a new world, drove around on the surface with the new diesel locomotive, had no collisions with trees or buildings.
Still doesn't work in the subway, the locomotive rams into the stone walls, but I believe this can be fixed by expanding within the subway curve tile.

If you want to test driving around, rotate the train in the direction you want to go before entering a junction. Attempting to change the angle you're driving while within a junction seems to almost always cause a derailment.

Additional context