* light github image for dark mode
* show message received status, remove chevrons in chat list
* show unread message status
* add message send error mark
* refactor alerts to use AlertManager
* show alert message on tapping undelivered message, simplify text-only alerts
* receiving messages in the background and sending local notifications
* show notifications in foreground and background
* presentation logic for notification options when app is in the foreground
* background refresh works
* remove async dispatch
