Implement 'wait' command - by doublep

By SomeTroglodyte:
- Re-hide Enable Portrait option on desktop
- Show required resource for upgrades
- Fix Right-Click attacks made no sound

Fix missing icons in civilopedia from main menu - By OptimizedForDensity

By Azzurite:
- Return to current game from main menu "Resume"

By alexban011:
- Fixed slider sound when opening screens
- Added confirmation option for "next turn"

Adding spaceship sprites for FantasyHex tileset - By GeneralWadaling
