Umstellung auf UTC Timestamp

lib/content_views/messages_page.dart

@@ -93,7 +93,7 @@ class _MessagesPageState extends State<MessagesPage> with ProducerMixin {
     message.text = text.text;
     message.from = _sid;
     message.subj = '';
-    message.time = now.toUtc().toIso8601String();
+    message.time = Util.toUnixMillisUtc(now.toUtc());
     message.read = true;
     message.id = await sbmessage.ChatMessage.getNextId();
 
@@ -128,8 +128,7 @@ class _MessagesPageState extends State<MessagesPage> with ProducerMixin {
     for (var message in messages) {
       _messages.add(types.TextMessage(
         author: message.from == _sid ? _user : _central,
-        createdAt:
-            DateTime.parse(message.time).toLocal().millisecondsSinceEpoch,
+        createdAt: message.time * 1000,
         id: message.id.toString(),
         text: "${message.subj}\n${message.text}",
       ));
@@ -215,7 +214,7 @@ class _MessagesPageState extends State<MessagesPage> with ProducerMixin {
 
       var chatMessagesShowed = ChatMessagesReceived();
       chatMessagesShowed.ids = chatMessageIds;
-      chatMessagesShowed.time = DateTime.now().toUtc().toIso8601String();
+      chatMessagesShowed.time = Util.toUnixMillisUtc(DateTime.now().toUtc());
 
       sendMessage(
         routingKey: Constants.messageTopicPublishPayload,