welp these tests kind of existed before

Added test that improvements can be built on their tiles

4.1.1-patch2

4.1.1-patch1

By Azzurite:
- Refactor: change GameSaver from singleton to single instance pattern & move autosave logic into GameSaver 
- Fix multiplayer turn checker potentially stopping turn checks for everyone that plays that game if a file was not found remotely 
- Initial Event Bus implementation & Event-based multiplayer updates 
- Fix screens not correctly being dispose()d 
- Refactor: Split options into multiple files 
- Fix images not being able to have their size set 
- Refactor: Extract PickerPane from PickerScreen 
- Fix turn check worker exception 

By SomeTroglodyte:
- Fix Autocracy Complete including unit test 
- Refactor UncivShowableException 
- Fix effect of new Beliefs not immediately visible in top bar 
- Unify editor style settings 
- SimpleHttp gets a connection timeout 
- Build warnings cleanup 

Fix crashes when a civ does not have a capital  - By OptimizedForDensity

By xlenstra:
- Added more unit tests for uniques; added missing unique implementations 
- Fixed a bug blocking special improvements on removable terrain features 

By itanasi:
- Fix Zone of Control 
- Assign Population Improvements 
- Add more comments on Editor Settings 

By JackRainy:
- A lot of smaller code/performance improvements 
- Correct check for the city connection quest