Proposing license addition and introducing mailmap

This commit adds a mailmap file to make it easier to associate
contrimutors who use different email addresses or names to commit to
this repository.

The reasoning behind the license change is to allow qaul.net to be
published on the Apple iOS app store.  Because our code repository is
licensed under the AGPL-3.0, we need to use the section 6 additional
permissions section of the AGPL to add this excemption to the license.
This is a change that all current copyright holders (CCed in the patch
mail) need to sign-off on.

Signed-off-by: Katharina Fey <kookie@spacekookie.de>

.mailmap

@@ -0,0 +1,6 @@
+Katharina Fey <kookie@spacekookie.de>
+Math Jud <jud@wachter-jud.net>
+Lux <lux@lux.name> <lux@ontheblueplanet.com>
+Lux <lux@lux.name> Lukas Kohler <lukas.kohler@ontheblueplanet.com>
+<tristankildaire@gmail.com> <deavmi@users.noreply.github.com>
+Jess 3Jane <me@jess.coffee> jess 3jane

README.md

@@ -54,8 +54,20 @@ Documentation is avaliable [here](https://docs.qaul.net).
 
 ## License
 
-qaul.net is free and open source software licensed under the
-[GNU Affero General Public License version 3 or later](licenses/gpl-3.0.md).
-
-To see all external code's licenses used in this project please 
-visit the [`licenses` directory](licenses).
+qaul.net is free and open source software licensed under the [GNU
+Affero General Public License version 3 or
+later](licenses/gpl-3.0.md).
+
+**Additional Permissions:** For Submission to the Apple App Store:
+Provided that you are otherwise in compliance with the AGPLv3 for each
+covered work you convey (including without limitation making the
+Corresponding Source available in compliance with Section 6 of the
+AGPLv3), the qaul.net developers also grant you the additional
+permission to convey through the Apple App Store non-source executable
+versions of the Program as incorporated into each applicable covered
+work as Executable Versions only under the Mozilla Public License
+version 2.0.
+
+A copy of both the AGPL-3.0 and MPL-2.0 license texts are included in
+this repository, along other external licenses for third-party code,
+and can be found in the [licenses](licenses) directory.