Adjust credits
Replace SpongyCastle credits with BouncyCastle

The package name is spongycastle to easy merges with OpenKeychain,
but the library being used is BouncyCastle with renamed packages.
Remove icon set credits
Reorder credits
Adjust credits
Change OpenKeychain links to APG
Change OpenKeychain strings to APG
Make QR code background white
Adjust Transfix configuration