Added Era Mechanics. Super Important

Quick update to add two more modifiers to the Desolation progress based on Great Power Rank. How big of a deal you are in the world matters a lot more now, and every upstart is a risk. Hopefully this will encourage players to more often engage Thucydides' Trap.

*I almost named this update Thucydides, but I'd like to push a bigger more substantive update for that later. This is just a bandaid.

Changed Polity from 10 to 5 Provinces.