Whisper v6 remove aesnonce

[gballet]

As per EIP-627, the Salt for symmetric encryption is now part of the payload. This commit does that.

[gballet]

@gluk256 Unit tests aren't finished yet, they are part of an upcoming commit so don't press the 'accept' button before they are there.

[fjl]

Why did you make this change?

[gballet]

Because the EIP-627 packet codes specifies that:

The message codes reserved for Whisper protocol: 0 - 127. Messages with unknown codes must be ignored, for forward compatibility of future versions.

Support for messages with codes 126 and 127 will be added in subsequent PRs.

[gluk256]

This change to EIP was made after discussion with Robert (Parity) several months ago.

[fjl]

@gballet please run gofmt -w -s

[fjl]

Travis says:

$ gofmt -s -d whisper/whisperv6/envelope.go
diff -u whisper/whisperv6/envelope.go.orig whisper/whisperv6/envelope.go
--- whisper/whisperv6/envelope.go.orig	2017-12-07 13:53:39.317628694 +0000
+++ whisper/whisperv6/envelope.go	2017-12-07 13:53:39.317628694 +0000
@@ -36,12 +36,12 @@
 // Envelope represents a clear-text data packet to transmit through the Whisper
 // network. Its contents may or may not be encrypted and signed.
 type Envelope struct {
-	Version  []byte
-	Expiry   uint32
-	TTL      uint32
-	Topic    TopicType
-	Data     []byte
-	Nonce    uint64
+	Version []byte
+	Expiry  uint32
+	TTL     uint32
+	Topic   TopicType
+	Data    []byte
+	Nonce   uint64
 
 	pow  float64     // Message-specific PoW as described in the Whisper specification.
 	hash common.Hash // Cached hash of the envelope to avoid rehashing every time.
@@ -63,13 +63,13 @@
 // included into an envelope for network forwarding.
 func NewEnvelope(ttl uint32, topic TopicType, msg *sentMessage) *Envelope {
 	env := Envelope{
-		Version:  make([]byte, 1),
-		Expiry:   uint32(time.Now().Add(time.Second * time.Duration(ttl)).Unix()),
-		TTL:      ttl,
-		Topic:    topic,
-		Data:     msg.Raw,
-		Nonce:    0,
+		Version: make([]byte, 1),
+		Expiry:  uint32(time.Now().Add(time.Second * time.Duration(ttl)).Unix()),
+		TTL:     ttl,
+		Topic:   topic,
+		Data:    msg.Raw,
+		Nonce:   0,
 	}

 	if EnvelopeVersion < 256 {

[fjl]

This is weird because the diff doesn't actually apply to envelope.go

[fjl]

Rebased. This should be OK now.