Update copyrights

Update copyrights

- Update the update-copyright script to include more contributors as well
  as correcting a few typos

- Correct a copyright address in the source code to now used address
  (dazo)

- Update copyright year to 2021

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20210609213231.22576-1-openvpn@sf.lists.topphemmelig.net>
URL: https://www.mail-archive.com/search?l=mid&q=20210609213231.22576-1-openvpn@sf.lists.topphemmelig.net
URL: https://sourceforge.net/p/openvpn/mailman/message/37299719/
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 05271322e7b5f453fe9d85310e500d3460ac8ca4)