Android service

[gavv]

Register foreground service with persistent notification to allow sender and receiver to run even if the app is closed. We would also need a button in the notification that stops and terminates the service.

See also #1, the implementation of these issues might overlap.

[BelchingJalapeno]

I'd like to work on this. There should be a separate notification for both the sender and receiver if they are both running at the same time, is that correct?

[gavv]

@BelchingJalapeno You're welcome! I think a single notification for the whole app would be more convenient. Sender and receiver threads could both belong to the same service with a single notification.

[gavv]

Merged!