Rework latifundium.

[pineappledan]

It now sounds to me like the easiest, most fair solution is the following:

• Latifundium takes a long time to build (15-25 turns on normal speed)
• On completion, immediately spawns a fig resource and plantation improvement on an adjacent tile, and claims that tile for Rome.
• Latifundium cannot be removed or pillaged.
• Cannot build latifundium adjacent to each other.
• Latifundium improves resources below it

Advantages:

• no delays or placeholders means no extra art assets
• no delays eliminates issues with savegame data, and storing fig placement/maturation on reloading.
• no delays means no complex timers, tile checking, maturation mechanics, or tile ownership checks
• no delays means no possibility for tile ownership to change between when a latifundium is constructed and the figs are completed
• no adjacency cuts down on total number of latifundia possible on map
• no adjacency means more varied landscapes (not just all purple plantations)
• Latifundium permanence means AI can't swap back and forth between plantation and latif.
• Latifundium permanence means AI can get plantations back

[adaneslavo]

Done.