FR-11: Decrypt file and remember associated metadata (so that we’ll be able to encrypt it back without asking user too many questions)

[skarpushin]

HTD:

• Expect: program will be able to resolve suggested encryption parameters based on previous decryption. Not only target filename and folder but also list of recipients
• Expect: upon encryption (later, if using these remembered settings) -- warn user if not all public keys and program can't encrypt it for same recipients as it was before decryption
• Expect In case of temporary folder was changed -- program will not loose track of files saved to previous temp folders. Newly decrypted files will be saved to new temp folder only.