discovery+routing: split 'routing' package on 'routing' and 'discovery'

In this commit the routing package was divided on two separete one,
this was done because 'routing' package start take too much responsibily
on themself, so with following commit:

Routing pacakge:
Enitites:
* channeldb.ChannelEdge
* channeldb.ChannelPolicy
* channeldb.NodeLightning

Responsibilities:
* send topology notification
* find payment paths
* send payment
* apply topology changes to the graph
* prune graph
* validate that funding point exist and corresponds to given one
* to be the source of topology data

Discovery package:
Entities:
* lnwire.AnnounceSignature
* lnwire.ChannelAnnouncement
* lnwire.NodeAnnouncement
* lnwire.ChannelUpdateAnnouncement

Responsibilities:
* validate announcement signatures
* sync topology with newly connected peers
* handle the premature annoucement
* redirect topology changes to the router susbsystem
* broadcast announcement to the rest of the network
* exchange channel announcement proofs

Before that moment all that was in the 'routing' which is quite big for
one subsystem.

split

routing/notifications.go

@@ -1,14 +1,13 @@
 package routing
 
 import (
-	"errors"
 	"fmt"
 	"net"
 	"sync/atomic"
 
 	"github.com/davecgh/go-spew/spew"
+	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/wire"
 	"github.com/roasbeef/btcutil"
@@ -277,17 +276,17 @@ type ChannelEdgeUpdate struct {
 // information required to create the topology change update from the graph
 // database.
 func addToTopologyChange(graph *channeldb.ChannelGraph, update *TopologyChange,
-	msg lnwire.Message) error {
+	msg interface{}) error {
 
 	switch m := msg.(type) {
 
 	// Any node announcement maps directly to a NetworkNodeUpdate struct.
 	// No further data munging or db queries are required.
-	case *lnwire.NodeAnnouncement:
+	case *channeldb.LightningNode:
 		nodeUpdate := &NetworkNodeUpdate{
 			Addresses:   m.Addresses,
-			IdentityKey: m.NodeID,
-			Alias:       m.Alias.String(),
+			IdentityKey: m.PubKey,
+			Alias:       m.Alias,
 		}
 		nodeUpdate.IdentityKey.Curve = nil
 
@@ -296,19 +295,19 @@ func addToTopologyChange(graph *channeldb.ChannelGraph, update *TopologyChange,
 
 	// We ignore initial channel announcements as we'll only send out
 	// updates once the individual edges themselves have been updated.
-	case *lnwire.ChannelAnnouncement:
+	case *channeldb.ChannelEdgeInfo:
 		return nil
 
 	// Any new ChannelUpdateAnnouncements will generate a corresponding
 	// ChannelEdgeUpdate notification.
-	case *lnwire.ChannelUpdateAnnouncement:
+	case *channeldb.ChannelEdgePolicy:
 		// We'll need to fetch the edge's information from the database
 		// in order to get the information concerning which nodes are
 		// being connected.
-		chanID := m.ChannelID.ToUint64()
-		edgeInfo, _, _, err := graph.FetchChannelEdgesByID(chanID)
+		edgeInfo, _, _, err := graph.FetchChannelEdgesByID(m.ChannelID)
 		if err != nil {
-			return err
+			return errors.Errorf("unable fetch channel edge: %v",
+				err)
 		}
 
 		// If the flag is one, then the advertising node is actually
@@ -321,13 +320,13 @@ func addToTopologyChange(graph *channeldb.ChannelGraph, update *TopologyChange,
 		}
 
 		edgeUpdate := &ChannelEdgeUpdate{
-			ChanID:          chanID,
+			ChanID:          m.ChannelID,
 			ChanPoint:       edgeInfo.ChannelPoint,
 			TimeLockDelta:   m.TimeLockDelta,
 			Capacity:        edgeInfo.Capacity,
-			MinHTLC:         btcutil.Amount(m.HtlcMinimumMsat),
-			BaseFee:         btcutil.Amount(m.FeeBaseMsat),
-			FeeRate:         btcutil.Amount(m.FeeProportionalMillionths),
+			MinHTLC:         m.MinHTLC,
+			BaseFee:         m.FeeBaseMSat,
+			FeeRate:         m.FeeProportionalMillionths,
 			AdvertisingNode: sourceNode,
 			ConnectingNode:  connectingNode,
 		}