Instead of as modules.
Replace *.read with read*, *.readArmored with readArmored*, etc.
Replace cleartext.readArmored with readArmoredCleartextMessage.
Replace message.fromText with Message.fromText, etc.
openpgp.encrypt, sign, encryptSessionKey, encryptKey and decryptKey now
return their result directly without wrapping it in a "result" object.
Also, remove the `detached` and `returnSessionKey` options of
openpgp.encrypt.
