Progress bar for changing national budget values

[jwrober]

Is your feature request related to a problem? Please describe. This is coming from LT78. Similar conditions to #2026. If I change the values of the national budget and click Apply, the game takes a long time to "do the math" and finalize what the Gold/Turn and Bulb/Turn values will be with the new settings. The game locks up until the process is complete.

Describe the solution you'd like I think adding a simple progress bar below the national budget dialog is the easiest solution. It progresses as the phases of the math progresses showing progress and letting you know that the game isn't locked up. Even if the map stays "locked" as in the unit selection stops spinning for example is fine.

Describe alternatives you've considered Solving why its taking so long in the first place is another way to look at it.

Additional context I personally have governors enabled, that might be part of the problem.

[lmoureaux]

Context: governors are slow