Make disk recording clients kickable.

Kick can no longer be called with groups locked.

disk.go

@@ -52,6 +52,12 @@ func (client *diskClient) Close() error {
 	return nil
 }
 
+func (client *diskClient) kick(message string) error {
+	err := client.Close()
+	delClient(client)
+	return err
+}
+
 func (client *diskClient) pushConn(id string, conn upConnection, tracks []upTrack, label string) error {
 	client.mu.Lock()
 	defer client.mu.Unlock()

group.go

@@ -268,6 +268,12 @@ func (g *group) getClientsUnlocked(except client) []client {
 	return clients
 }
 
+func (g *group) getClient(id string) client {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	return g.getClientUnlocked(id)
+}
+
 func (g *group) getClientUnlocked(id string) client {
 	for idd, c := range g.clients {
 		if idd == id {

webclient.go

@@ -948,10 +948,7 @@ func (c *webClient) kick(message string) error {
 }
 
 func kickClient(g *group, id string, message string) error {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-
-	client := g.getClientUnlocked(id)
+	client := g.getClient(id)
 	if client == nil {
 		return userError("no such user")
 	}