Allow changing shape of vehicle parts without reinstalling

[Saicchi]

Summary

Interface "Allow changing shape of vehicle parts without reinstalling"

Purpose of change

Vehicle parts shape and orientation are purely comestic, but you can't change them without uninstalling and installing the part.

Describe the solution

Add a new menu to the vehicle examine menu, shaPe. It allows the player to change the shape instantly free of cost.

Describe alternatives you've considered

Make the menu return to the base state after changing shape. This speeds up things if players want to change the shape of parts on different tiles.

Testing

• Changing shape is purely comestic and does not affect the vehicle at all

Additional context

It was my first time dealing with the vehicle code, it's confusing how it all works, and since I don't know what to expect from changing the vehicle part variant, I might have messed up in vpart_shapes, though at the moment it seems to be working fine.

I wanted to pick a key closer to ESC but s, a and e were taken, so I went with p instead of h.

[jagoly]

IMO making shape changes should take a small amount of time, something like 1/4 of the install time. I think this would feel better for players, like they are actually modifying the vehicle, even if it is just to look cooler.

[Saicchi]

That adds unnecessary complexity for a function that has no impact in-game and is purely cosmetic.