Normalize authors through a mailmap file

This is used from at least git shortlog.

.mailmap

@@ -0,0 +1,18 @@
+# Unify user identities
+Christian Perrier <bubulle@debian.org>
+<ian@davenant.greenend.org.uk> <ian@anarres>
+<ian@davenant.greenend.org.uk> <ian@liberator>
+<jackyf@debian.org> <jackyf@1501-debian>
+Michael Vogt <mvo@debian.org> <egon@debian-vm>
+<mvo@debian.org> <egon@bottom>
+<mvo@debian.org> <egon@debian-devbox>
+<mvo@debian.org> <egon@pop>
+<mvo@debian.org> <egon@tas>
+<michael.vogt@ubuntu.com> <mvo@ubuntu.com>
+# Name changes
+Peter Krefting <peterk@debian.org>
+# Email as user name
+Christian Perrier <bubulle@debian.org> bubulle@debian.org <>
+Julian Andres Klode <jak@debian.org> jak@debian.org <>
+Loïc Minier <lool@dooz.org> lool@dooz.org <>
+Martin Pitt <martin@piware.de> martin@piware.de <>