Origins and updated mod

What's Changed

• Change tests to use save files not in the main repo by @chennin in #143
• Rewrite the mod to no longer use (now nonexistent) in-game browser by @MichaelMakesGames in #150
• Save and display country origins by @MichaelMakesGames in #152
• Use alembic to automatically migrate game DBs by @MichaelMakesGames in #153

Full Changelog: v6.1...v6.2