Introduce deliveredClientMap

Adds more semantics to map[string]string. Simplifies the complicated
mapStringStringCasemapMap type.

downstream.go

@@ -997,7 +997,7 @@ func (dc *downstreamConn) welcome() error {
 
 		// Fast-forward history to last message
 		for target, entry := range net.delivered.innerMap {
-			delivered := entry.value.(map[string]string)
+			delivered := entry.value.(deliveredClientMap)
 			ch := net.channels.Value(target)
 			if ch != nil && ch.Detached {
 				continue

irc.go

@@ -600,12 +600,12 @@ func (cm *membershipsCasemapMap) Value(name string) *memberships {
 	return entry.value.(*memberships)
 }
 
-type mapStringStringCasemapMap struct{ casemapMap }
+type deliveredCasemapMap struct{ casemapMap }
 
-func (cm *mapStringStringCasemapMap) Value(name string) map[string]string {
+func (cm *deliveredCasemapMap) Value(name string) deliveredClientMap {
 	entry, ok := cm.innerMap[cm.casemap(name)]
 	if !ok {
 		return nil
 	}
-	return entry.value.(map[string]string)
+	return entry.value.(deliveredClientMap)
 }

upstream.go

@@ -1754,7 +1754,7 @@ func (uc *upstreamConn) appendLog(entity string, msg *irc.Message) (msgID string
 			return ""
 		}
 
-		delivered = make(map[string]string)
+		delivered = make(deliveredClientMap)
 		uc.network.delivered.SetValue(entity, delivered)
 
 		for clientName, _ := range uc.network.offlineClients {

user.go

@@ -55,6 +55,8 @@ type eventChannelDetach struct {
 
 type eventStop struct{}
 
+type deliveredClientMap map[string]string // client name -> msg ID
+
 type network struct {
 	Network
 	user    *user
@@ -62,7 +64,7 @@ type network struct {
 
 	conn           *upstreamConn
 	channels       channelCasemapMap
-	delivered      mapStringStringCasemapMap // entity -> client name -> msg ID
+	delivered      deliveredCasemapMap
 	offlineClients map[string]struct{} // indexed by client name
 	lastError      error
 	casemap        casemapping
@@ -80,7 +82,7 @@ func newNetwork(user *user, record *Network, channels []Channel) *network {
 		user:           user,
 		stopped:        make(chan struct{}),
 		channels:       m,
-		delivered:      mapStringStringCasemapMap{newCasemapMap(0)},
+		delivered:      deliveredCasemapMap{newCasemapMap(0)},
 		offlineClients: make(map[string]struct{}),
 		casemap:        casemapRFC1459,
 	}