Better error message for multiplayer games that get corrupted data from the server

chore: more direct 'can change state' propagations

Cleanup of policy screen

Removed static references from policy buttons

Civilopedia entry for policy links to units and buildings that it enables/disables

Resolved  - wonders with no tech requirement displayed in separate category

Attacking of any sort prevents udo of unit move

By vegeta1k95:
- Modding: allow mods to supply custom fonts 
- Fix TextureArraySpriteBatch missing method issue 
- UI Helper: GUI class 

By Gualdimar:
- Option to disable max zoom limit 
- Slider tip permanent by default