Add object to center of starfield loading screen

[raucao]

At the moment, the starfield can easily be mistaken for snow, due to it not being black bg and white fg. Also, it'd be way more fun if there were some kind of object (e.g. Botka from above, a spaceship, whatever else flies in space, ...) in the middle, and we could even add support for a bit of light steering, so it's even more fun to wait.