Skinnable vehicles

**What do you want to see?**
The ability to have multiple icons/portraits for vehicle hulls, which can be chosen from when creating a design. For instance, the Constitution-class cruiser might have one cruiser image, while the Constellation-class cruiser might have another.

**How would it help players?**
Distinguish their ships from each other so they are more easily recognizable and just look cool

**Alternatives**
?

**Screenshots and mockups**
See MOO2 where there are multiple icons to choose from for each ship hull.

**Things to consider**
* How to name the files in the shipset so they can be recognized as alternate skins?
* What to do if one skin has a portrait but not an icon or vice versa (scale it up/down? leave it out?)
* Where are we going to get all this ship art?
* Could this be applied to other in-game elements such as facilities, components, etc?