Rework immigration

- POP migration does not favor any continent
- All POPs favor countries with social reforms
- All POPs favor countries with democracy, voting rights for their class, and citizenship for their culture.
- All POPs favor countries with their culture and cultural unions
- All POPs favor countries with their religion or secularism
- All POPs favor countries that are satellites or in the sphere of their current country
- All POPs favor countries with low taxes on their class, and avoid countries with high taxes on their class
- All POPs avoid countries with high militancy, with 5 bringing immigration to a halt
- Farmer and Labourer POPs slightly less likely to migrate to countries that allow slavery
- Soldier and Officer POPs more likely to migrate to countries with Jingo-ism and Pro-Military, and less likely for Anti-Military and Pacifism
- Capitalist POPs are more likely to migrate to countries with Free Trade and Laissez-Faire, and less likely with State Capitalism and Planned Economy
- Primary and Accepted Culture POPs favor migrating to your colonies over emigrating to another nation, with the opposite true for non-accepted. This was true before, but the effect has been enhanced.
- War and war exhaustion now increase emigration from your country.

Original mod: http://forum.paradoxplaza.com/forum/showthread.php?506285-POP-Migration-Mod