Paralellise update gamestate & modifiers

[wvpm]

Stacked on top of #739

Note updating adjecencies inside the country is commented out.
This really should've never been placed there as recalculating it is expensive and can't be multithreaded easily.
Also the outcome rarely changes. It can only change when provinces change owner or our capital changes province.

[schombert]

doesn't this call manage_national_stockpile which ultimately can call add_buy_up_to_order (for example), which is thread safe, but will make the order of the contents of buy_up_to_orders relative on the speed at which the threads in the pool finish (and their number), meaning that the order in which they are resolved in GoodMarket::execute_orders will vary based on timing, meaning that deterministic lockstep will not hold for multiplayer?

[wvpm]

The market doesn't care about ordering.

[schombert]

Ah, fascinating. I assumed that you were trying to replicate the v2 economy, where items are drained from the market in order (specifically in rank order) and nations later in the order simply can't get anything. Doing equal division is also what version 1.0 of PA did, and for the same reasons (it makes it possible to parallelize the economy). Since this was the one big difference between the PA economy and the V2 economy in 1.0, I imagine that your economy system will behave a lot like the 1.0 PA economy. So be warned that this creates some substantial differences in gameplay.