By OptimizedForDensity:
- Add unit type to Civilopedia
- Fix bug related to resuming games
- Fix mod translation file generation

By xlenstra:
- Occupied cities have +2 extra unhappiness
- Added 'without resource' conditional
- Added a unique for destroying improvements on attack

Add missing string to the translations template file  - By estorski

Made invisible units not become visible just by being next to an owned tile.  - By kralinc