Merge pull request #342 from darktable-org/po/mailmap

Update .mailmap for proper generation of dt AUTHORS file.

Author: LebedevRI

.mailmap

@@ -19,3 +19,6 @@ Matthieu Volat <mazhe@alkumuna.eu> Matthieu <mazhe@alkumuna.eu>
 Matthieu Volat <mazhe@alkumuna.eu> Matthieu Volat <matthieu.volat@ujf-grenoble.fr>
 
 Shita Yuuma <m@crat.jp>
+
+Hanno Schwalm <hanno@schwalm-bremen.de>
+Hanno Schwalm <hanno@schwalm-bremen.de> hanno@schwalm-bremen.de <hanno@schwalm-bremen.de>