Fixed Bad Production Focus Valuer

Fixed the fact the production focus overvalues unemployed citizens by
checking plot value against citizen value instead of relying on whether
the best specialist focus yield is better than the default specialist
focus yield.
Two New Parameters

- Fix for bad production focus valuer
- Fix for AI sending propaganda diplomats to players with whom it would
not receive a propaganda bonus
Fixed AI Wanting No Bonus Propaganda Diplomats

Fixed the AI wanting propaganda diplomats with players with whom it
would not receive a tourism boost.