- Notifications.alert_time → Notifications.flash_time,
more evocative of what these "alerts" actually do
- Change default for the above from 0 to 5, since now push rules already
control precisely what to enable or disable these alerts for
- Notifications.urgent_alert_time → Notifications.highlight_flash_time,
"highlight" is the term used in the matrix doc
When messages are selected in the timeline, change the chat header's
mode to show how many messages are selected and offer copy, remove and
deselect buttons.
