.gitignore added; HDI and emigration changes

- .gitignore files that are in the "Release" folder, which are output
files.
- HDI annual change cap changed to 10% per year from 25%
- Country info window now displays numerical country and world average
HDI values.
- Countries with higher gov't approval and/or stability now have lower
emigration than those with lower approval and/or stability (likely a bug
in the original game).