Religion button respects unique "hidden from users" modifier

Trigger 'capture city' as a unit trigger

By tuvus:
- Worker AI Rework
- AI doesn't counteroffer and request a treaty on the same turn
- 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