Added a file for mapping emails to persons in Git.

https://developer.atlassian.com/blog/2017/06/aliasing-authors-in-git/

$ git summary

 project  : ogs
 repo age : 8 years
 active   : 1859 days
 commits  : 12781
 files    : 4757
 authors  :
  3162	Dmitri Naumov      24.7%
  2755	Thomas Fischer     21.6%
  2498	Lars Bilke         19.5%
  1317	Karsten Rink       10.3%
  1095	Christoph Lehmann  8.6%
  1045	Norihiro Watanabe  8.2%
   711	Wenqing Wang       5.6%
    60	Yonghui Huang      0.5%
    21	Francesco Parisio  0.2%
    19	Renchao Lu         0.1%
    19	Chaofan Chen       0.1%
    17	Jasper Bathmann    0.1%
    16	Xing-Yuan Miao     0.1%
    10	Keita Yoshioka     0.1%
     9	Haibing Shao       0.1%
     7	Marc Walther       0.1%
     6	Tianyuan Zheng     0.0%
     5	OGS Bot            0.0%
     3	Jan Thiedau        0.0%
     2	Norbert Grunwald   0.0%
     2	Carolin Helbig     0.0%
     1	Thomas Nagel       0.0%
     1	Myles English      0.0%

.mailmap

+Carolin Helbig <carolin.helbig@ufz.de>
+Chaofan Chen <chaofan.chen@ufz.de>
+Christoph Lehmann <chleh@users.noreply.github.com> <christoph.lehmann@ufz.de>
+Dmitri Naumov <dmitri.naumov@ufz.de> <github@naumov.de>
+Dmitri Naumov <dmitri.naumov@ufz.de> Dmitrij Naumov <dmitrij@naumov.de>
+Dmitri Naumov <dmitri.naumov@ufz.de> Dmitry Yu. Naumov <dmitri.naumov@ufz.de>
+Francesco Parisio <francesco.parisio@ufz.de>
+Francesco Parisio <francesco.parisio@ufz.de> fparisio <francesco.parisio@protonmail.com>
+Haibing Shao <haibing.shao@ufz.de> <36633245+HBShaoUFZ@users.noreply.github.com>
+Haibing Shao <haibing.shao@ufz.de> HBShaoUFZ
+Jan Thiedau <jan.thiedau@bgr.de> <44462589+ThieJan@users.noreply.github.com>
+Karsten Rink <karsten.rink@ufz.de>
+Keita Yoshioka <keita.yoshioka@ufz.de>
+Lars Bilke <bilke@users.noreply.github.com> <lars.bilke@ufz.de> <larsbilke83@googlemail.com>
+Myles English <mylesenglish@gmail.com>
+Norbert Grunwald <n.g.boettcher@gmail.com>
+Norihiro Watanabe <norihiro.w@gmail.com> <norihiro.watanabe@aist.go.jp> <norihiro.watanabe@ufz.de>
+OGS Bot <larsbilke@web.de>
+Thomas Fischer <thomas.fischer@ufz.de> <123_tom_dabei@web.de> <Thomas.Fischer@ufz.de>
+Thomas Fischer <thomas.fischer@ufz.de> Tom Fischer <Thomas.Fischer@ufz.de>
+Wenqing Wang <wenqing.wang@ufz.de>
+Yonghui Huang <huangyh56@gmail.com>
+Yonghui Huang <huangyh56@gmail.com> Yonghui56 <huangyh56@gmail.com>
+Yonghui Huang <huangyh56@gmail.com> Yonghui <huangyh56@gmial.com>
+Tianyuan Zheng <ichbinzty@gmail.com>
+Jasper Bathmann <jasper.bathmann@ufz.de>
+Renchao Lu <renchao.lu@gmail.com>
+Thomas Nagel <thomas.nagel@ufz.de>
+Marc Walther <marc.walther@ufz.de>
+Xing-Yuan Miao <miaoxingyuan@live.cn> <xing-yuan.miao@ufz.de>
+Xing-Yuan Miao <miaoxingyuan@live.cn> xymiao
+Xing-Yuan Miao <miaoxingyuan@live.cn> xingyuanmiao <xingyuanmiao@users.noreply.github.com>