AppImage: Implement zsync update support.
Linux: Require Flatpak to be false to be marked as an AppImage.
Windows: Add Xbox support.
GameDB: Add Gears of War: Reloaded.
GameDB: Add AKIBA’S TRIP: Hellbound & Debriefed.
GameDB: Reduce allocations in get_installed_games.
GameDB: Fix parse using wrong cache location.
GameDB: Add AKIBA'S TRIP: Undead & Undressed.
Updater: Use serde for deserialization.
MacOS: Add GOG Galaxy support.