Feature request: Preview button

[beccabunny]

To avoid having to save the map, open it in the game and finding the system, it would be nice to have a "preview" button in the system tab that shows how the selected system looks in game, which means rendering the stars in the background and removing the UI elements like the planet orbits and the habitable zone. An alternative is to be able to select individually which of these UI elements to show, plus a button for the background stars