Update .mailmap to unify and clean up odd names and e-mail addresses

To make the best use of this, have a look at the --use-mailmap option.
In particular git-log and git-shortlog makes use of it.  Also search
for mailmap in the git-log man page, for more ways to use this
remapping (format strings to --pretty).

Otherwise, to make use of the mailmap remapping by default do:

     $ git config [--global] log.mailmap true

.mailmap

@@ -1 +1,13 @@
-James Yonan <james@openvpn.net>      james <james@e7ae566f-a301-0410-adde-c780ea21d3b5>
+Adriaan de Jong <dejong@fox-it.com>             <adriaan@adriaan-VirtualBox.(none)>
+David Sommerseth <dazo@eurephia.net>            <dazo@users.sourceforge.net>
+Gert Doering <gert@greenie.muc.de>              <gd@medat.de>
+Gert Doering <gert@greenie.muc.de>              <gert@fbsd74.ov.greenie.net>
+Gert Doering <gert@greenie.muc.de>              <gert@fbsd90.ov.greenie.net>
+Gert Doering <gert@greenie.muc.de>              <gert@mobile.greenie.muc.de>
+James Yonan <james@openvpn.net>                 <james@e7ae566f-a301-0410-adde-c780ea21d3b5>
+Jan Just Keijser <janjust@nikhef.nl>            <janjust@nikhef.nl>
+JuanJo Ciarlante <jjo@google.com>               <jjo+ml@google.com>
+Karl O. Pinc <kop@meme.com>                     <kop@mofo.meme.com>
+Robert Fischer <ml-openvpn@trispace.org>        <ml-openvpn@trispace.org>
+Samuli Seppänen <samuli@openvpn.net>            <samuli@openvpn.net>
+Seth Mos <seth.mos@dds.nl>                      <seth.mos@dds.nl>