Diplomacy Buildings Rework

Reworks the Diplomacy Buildings. Each age now has a single Diplomacy building, granting a flat Influence yield in addition to Happiness and one other yield (listed below). This building is: - Ageless and Persistent (available to build in all ages). - only marked as Diplomacy Building (and nothing else). - lacking adjacency yields. Diplomacy buildings: - Antiquity age: Monument (Culture) - Exploration age: Inn (Food) - Modern age: Radio Station (Culture) Other buildings which previously had an Influence yield are no longer marked as Diplomacy buildings and no longer have such a flat Influence yield. They have gained other bonuses instead: - Villa : Now a regular culture building (base yield and adjacency). In addition, it receives +1 Influence from the Monument and any Wonder in the city. - Dungeon: Now also grants +1 Production on Fortified Districts. - Guildhall: Completely reworked. +3 Gold. +1 Gold on Resources (Warehouse bonus). +1 Gold from Distant Land Treasure Resources (counts as adjacency bonus). Can be purchased in Towns. - Opera House: Now also grants +10% Production towards Wonders and Projects. During the Happiness crisis, towns can now build Arenas instead of Villas.