Fixed Infinite map zoom

We set the PlanetariumCamera to the selected vessel and after this we removed this new "entry" from the PlanetariumCamera.fetch.targets list. (FocusFragment.cs:45) If you switched back to the map view the PlanetariumCamera is set to a vessel that doesn't exists on the PlanetariumCamera.fetch.targets list anymore.

This will fix #188
hm yea i think if we would like to use "buttons" for this but we are using state-buttons. You only have to deselect the current selection to go back to your active vessel.