World Fair planning fixed to become less spammy under certain conditions

[rogerburks]

While this likely occurs only under highly specific circumstances, the World's Fair planning event can become spammy for certain French primary tags such as Martinique.

This seems to be due to a modifier for tags with a French primary culture, but which do not have an Eiffel Tower built yet. The Eiffel Tower is linked to an 1889 World's Fair known as the Exposition Universelle, and the decision build_the_eiffel_tower requires the country flag world_fair_planner. This serves as evidence that the relatively extreme modifier is meant specifically for France, and not for any tags that can never build the Eiffel Tower.

I was previously puzzled over why primary_culture was used instead of tag = FRA in the event. Then I realized that France occasionally changes tags through the course of the game. Therefore, have adjusted the fix to scope France based on primary_culture and capital.

If we want to be especially funny, we could allow Martinique to build the Eiffel Tower, but I think there is no way for Martinique to annex Paris before France can build the Eiffel Tower.

This is described in issue #87

[moretrim]

I’m using the opportunity to add similar missing capital checks wherever needed. I still need to test the resulting commit however.