Modding: Unbuildable units can still be upgraded to

Fallback image for modded buildings - see 

Fallback image for modded buildings - see 

Fallback image for modded techs - see 

Thinner stats table so we can see more of the tiles

Readded stats drilldown

By vegeta1k95:
- Rework of City Screen: new Great People list + misc changes 
- Huge update of Technology Picker screen UI (Civ 5), new original icons + misc changes 

By FiretronP75:
- Continent and Islands 
- Prevent ice on mountains, and atolls under ice, resources on snow, in flat earth ice walls. 
- Make map editor respond to max zoom setting. 

AbsoluteUnits - Mongolian Uniques  - By letstalkaboutdune

Fix new "temperature" map setting not translatable  - By Ouaz