Introduce mailmap for accurate git log and other commands. (#2017)

.mailmap

@@ -0,0 +1,16 @@
+Leah Neukirchen <leah@vuxu.org> <chneukirchen@gmail.com>
+Mickaël Riga <mig@mypeplum.com>
+James Tucker <jftucker@gmail.com>
+Ravil Bayramgalin <brainopia@evilmartians.com>
+Pavel Rosicky <pavel.rosicky@easy.cz>
+Yuichiro Kaneko <spiketeika@gmail.com>
+Yoshiyuki Hirano <yhirano@me.com>
+Dima Fatko <fatkodima123@gmail.com>
+Yudai Suzuki <3280467rec@gmail.com>
+Marc-André Cournoyer <macournoyer@gmail.com>
+Megan Batty <megan@stormbrew.ca> <graham-git@stormbrew.ca>
+Megan Batty <megan@stormbrew.ca> <graham@graham-battys-macbook.local>
+Richard Schneeman <richard.schneeman@gmail.com> <richard.schneeman+foo@gmail.com>
+Wyatt Pan <wppurking@gmail.com>
+Kazuya Hotta <khotta116@gmail.com>
+Julik Tarkhanov <me@julik.nl>