Another boring version with mostly technical updates, fixes, etc. Some interface improvements as well. No gameplay changes this time.

- [misc] Configuration (resolution settings, audio, etc) is persistent and not overwritten upon each update (you will see this effect upon the nearest update).
- [misc] Proper icon for .exe file.
- [misc] Installer (for non Steam distribution), no more .zip files.

- [interface] Unexplored planets have unexplored planet icon instead of planet type icon.
- [interface] Finished unique ship icons for different race types (all ship types included).
- [interface] Added ship icons to squadron details screen.

- [fix] Fixed prestige gain per era.
- [fix] Fixed squadron details screen (rare glitch).