Features:
* Share to topic feature (#131, thanks u/emptymatrix for reporting)
* Ability to pick a default server (#127, thanks to @poblabs for reporting and testing)
* Automatically delete notifications (#71, thanks @arjan-s for reporting)
* Dark theme: Improvements around style and contrast (#119, thanks @kzshantonu for reporting)

Bug fixes:
* Do not attempt to download attachments if they are already expired (#135)
* Fixed crash in AddFragment as seen per stack trace in Play Console (no ticket)

Other thanks:
* Thanks to @rogeliodh, @cmeis and @poblabs for testing
