Option to automatically hide ships in UI that don't have a ship allocated, and get rid of red X for refunds

[corfe83]

The red X doesn't give enough to be useful, and can be accidentally clicked. Hiding allows you to juggle a larger set of ships, especially now that civilian ships are repurposed, and as we introduce more ship types in future updates

[corfe83]

Sometimes you need to have cargo ships for economy development, other times you need armored cruisers for pushing. As we grow in number of ships, maybe we should have sets of ships, one set for pushing, one set for farming? Or similar?