📧 Update git .mailmap file

This aliases my own email address, as well as the svn-generated email
addresses for @shugo, @nobu, and @hsbt.

Author: nevans

.mailmap

@@ -0,0 +1,13 @@
+nicholas a. evans <nick@rubinick.dev>
+nicholas a. evans <nick@rubinick.dev> <nick@410labs.com>
+nicholas a. evans <nick@rubinick.dev> <nick@ekenosen.net>
+nicholas a. evans <nick@rubinick.dev> <nicholas.evans@gmail.com>
+
+Shugo Maeda <shugo@ruby-lang.org>
+Shugo Maeda <shugo@ruby-lang.org> <shugo@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+Nobuyoshi Nakada <nobu@ruby-lang.org>
+Nobuyoshi Nakada <nobu@ruby-lang.org> <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+Hiroshi SHIBATA <hsbt@ruby-lang.org>
+Hiroshi SHIBATA <hsbt@ruby-lang.org> <hsbt@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>