Introduce unlock method for keys: passphrase is set as attribute of key and used
to decrypt required secret key packets on demand. Directly access config module in armor.js.
Key method getPrivateKeyPacket returns key packets by ID (optionally decrypted).
Message method decrypt returns new message with packetlist of decrypted message.
Add CRLF conversion to literal data packet. Packetlist: make filterByTag variadic,
add findPacket method. Keep state isDecrypted in secret key packet, don't decrypt
if already decrypted. Add mapToHex method to keyid. Simplify emailRegEx.