Starting in later eras triggers era uniques in all previous eras  - By xlenstra

Generalize Great Wall unique  - By OptimizedForDensity

By nacro711072:
- fix wrong happiness point on resume game if adopted 'Cultural Diplomacy' policy.
- fix no victoryTypes for the first time gaming with "quick game" opion.
- Fixed: double unit while loading game from customFile.

By xk730:
- Increased help button size

Unit art updates  - By GeneralWadaling