* patches/defauth-keyfile.patch: Fix using both polkit and keyfile.
  * brltty.postinst: Do not make /etc/brlapi.key readable by world any more,
    polkit should be enough.
  * patches/defauth-polkit: Default to using both policykit and
    /etc/brlapi.key to authenticate brlapi clients.

instead of /etc/brlapi.key.

  * Cherry-pick upstream r4926 to fix minus sign in vtsp.1.
  * Cherry-pick upstream r4927 to fix a typo.
  * debian/NEWS: Remove bullets, fix version number.
  * Override package-contains-empty-directory lib/brltty/rw/ which is on
    purpose.
  * debian/control:
    - Drop duplicate Priority field.
    - Fix duplicate short descriptions.