docs: Closer cropped icon for better viewing

Custom icons for mkdocs

Fix tests

docs: better unique parameter documentation

terrainFilter now accommodates nationFilter for owner

Remove double icons from airsweep/nuke battle table

Fade unit icon in overview if not idle

By WhoIsJohannes:
- Performance improvements 
- Cache civ uniques while refreshing world map tiles. 

Allow to reveal explored resources from a city's demanding resources in `CityOverviewTab`  - By chr56

By SomeTroglodyte:
- Visual clue a load game from clipboard is underway 
- Fix border case crash with lone AI winning on turn 0 
- Allow modders to use culture/faith conversion without providing the icons 
- "can be promoted" notification only when it's actually new 
- Fix wrapping for promotions in unit overview 

Don't return 401 when auth is disabled  - By Chris1712