Religion button respects "hidden from users" modifier on uniques

Returning old function, because LibGDX function is a one-way set

By tuvus:
- Worker AI Rework 
- AI doesn't counter offer and request a defesive pact, open borders or research pact at the same time 
- Civs now have a 50% chance of picking their favored religion 

By SeventhM:
- Fix stat on tile uniques doubling on improvement tiles 
- Avoid crash if "Only available" unique in policy branch has 2 or more params 
- Allow for improvement removal "improvements" 

Randomize seed checkbox  - By remdu

Modders wiki updating  - By Why-not-now