Civ Culture

[kjniemela]

Players should be able to build improvements that generate "culture" toward their Civilization, which improves loyalty.

• [ ] Culture yields.
• [ ] Culture accumulation.
• [ ] Culture and Knowledge spread tile-by-tile.
• [ ] Culture and Knowledge spread via traders.
• Tile should "flip" to another civ if loyalty is low enough.
• Enemy units should lower loyalty on adjacent tiles.

[kjniemela]

I think Loyalty will be needed for basic gameplay to work, but not Culture, so I'll split this ticket in two and bump the Loyalty ticket up to the Alpha release milestone.