Make already received messages available in Flightmode/No Network situation

[pm-pm]

When i want to read the already received messages/information in Flightmode or without Network Connection (Trains in Germany) i only get the information: "No connection to server".

Please make in this case the already received message readable and shown then an additional information that network connection is not existing.

[jmattheis]

Seems like a good idea to use cached messages when network is not available.

[PanderMusubi]

Another reason to have cached content is for when there is network but the server is down. Especially important when Gotify was used for reporting on the status of the server it runs on.