Umstellung auf UTC Timestamp

lib/network_messages/chat_message.g.dart

@@ -18,7 +18,7 @@ MessageContent _$MessageContentFromJson(Map<String, dynamic> json) =>
     MessageContent()
       ..text = json['text'] as String
       ..subj = json['subj'] as String
-      ..time = json['time'] as String;
+      ..time = (json['time'] as num).toInt();
 
 Map<String, dynamic> _$MessageContentToJson(MessageContent instance) =>
     <String, dynamic>{