Features request: Add file encryption/decryption/signature/verification features

[Metaphorme]

Dear developers!

PGPro is a great open source, lightweight PGP tool. As iOS continues to improve features related to file management, it would be very helpful if we could use PGPro to encrypt, decrypt, sign, and verify files.

Thank you for your patience and maintenance in creating the work of art that is the PGPro.😊