New features:
* Support for five priorities (via X-Priority, #24) mapped to Android priorities
* Support for notification title (via X-Title, #24)
* Support for tags and emojis (via X-Tags, #24)

Usability improvements:
* Support deep links for https://ntfy.sh/.. topics (#20)
* Add "clear all notifications" menu item (#21)
* Auto-complete for "use another server" feature (#13)
* Expanding notifications to read entire text (no ticket)
* Color "Permanently delete" buttons red (no ticket)

