fix timestamp syntax in MARKREAD

irc/getters.go

@@ -4,6 +4,7 @@
 package irc
 
 import (
+	"fmt"
 	"net"
 	"sync/atomic"
 	"time"
@@ -493,7 +494,7 @@ func (client *Client) GetReadMarker(cfname string) (result string) {
 	t, ok := client.readMarkers[cfname]
 	client.stateMutex.RUnlock()
 	if ok {
-		return t.Format(IRCv3TimestampFormat)
+		return fmt.Sprintf("timestamp=%s", t.Format(IRCv3TimestampFormat))
 	}
 	return "*"
 }