When viewing a media in the media preview, you can delete it by pressing
a delete button on the action bar. It will then ask you to confirm your
choice. If you confirm, it will delete the attachment from the database
and from disk. If it was the only attachment for that message, the
message itself will also be deleted.
This was a holdover from Signal's origins as a pure SMS app.
It causes problems, depends on undefined device specific behavior,
and should no longer be necessary now that we have all the
information we need to E164 all numbers.
// FREEBIE
