lots of important fixes

- DPFS container is fixed
- SD Savegame is fixed
- added slot0x25KeyX load
- added regex for titile ID
- added aes_keys.txt import
- sd savegame listing is fixed (uninitialized won't be listed any more)
- error handling is improved (removed asserts and replaced with return values)
- UI is now functional
- config is now checked in main

src/core/importer.h

@@ -55,6 +55,8 @@ struct Config {
     std::string safe_mode_firm_path; ///< Path to safe mode firm (A folder) (Sysdata 1)
     std::string seed_db_path;        ///< Path to seeddb.bin (Sysdata 2)
     std::string secret_sector_path;  ///< Path to secret sector (New3DS only) (Sysdata 3)
+
+    // Sysdata 4 is aes_keys.db (slot0x25KeyX)
 };
 
 class SDMCImporter {