dependency injection
The places still using the .shared property are cases where there is no
view controller from which to (easily) get the appropriate instance,
such as user activity and X-Callback-URL handling. These uses will need
to be revisited once there are multiple MastodonControllers.
See #16
Closes#49
This is a workaround for UIKit's built-in suggested context menu actions
not working as expected, and should be replaced with the system thing if
it becomes possible.
Shadowfacts