Refactor api (#6)

* Refactor library, remove duplicates

* Rebuild structure to use Messages and Signature models

* Use PGPSplitMessage

* Remove signature model

* Various fixes

* Add helpers with tests

* Fixes, add some docs, add tests

* Add attachment helpers

* Add helpers Symmetric encryption

* Edit docs + examples

* Rename kr to keyRing

* Various fixes for documentation

* Edit JSON handling functions, add decrypt keyring via token

* Add proposal changes doc

* Fix CI

* Drop *Message functions, join CleartextMessage and BinaryMessage

* Change canonicalization and trimming only to text signatures

* Add cleartextsignature, detach signature from message model, move helpers

* Documentation, remove optional parameters

* Move verification to separate model

* Don't return message in VerifyDetached

* Update table of contents in readme

* Appease golint

* Run go fmt

* Rename Encrypt/DecryptMessageWithPassword to ..WithToken

These functions shouldn't be used with user-provided passwords,
as they don't do any key-stretching.

* Change key generation usernames

constants/armor.go

@@ -6,6 +6,7 @@ const (
 	ArmorHeaderVersion = "GopenPGP 0.0.1 (" + Version + ")"
 	ArmorHeaderComment = "https://gopenpgp.org"
 	PGPMessageHeader   = "PGP MESSAGE"
+	PGPSignatureHeader = "PGP SIGNATURE"
 	PublicKeyHeader    = "PGP PUBLIC KEY BLOCK"
 	PrivateKeyHeader   = "PGP PRIVATE KEY BLOCK"
 )

constants/cipher.go

@@ -9,3 +9,10 @@ const (
 	AES192    = "aes192"
 	AES256    = "aes256"
 )
+
+const (
+	SIGNATURE_OK          int = 0
+	SIGNATURE_NOT_SIGNED  int = 1
+	SIGNATURE_NO_VERIFIER int = 2
+	SIGNATURE_FAILED      int = 3
+)