Add new script to generate AUTHORS and regenerate AUTHORS (fixing a few new dups too)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

hack/generate-authors.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -e
+
+cd "$(dirname "$(readlink -f "$BASH_SOURCE")")/.."
+
+# see also ".mailmap" for how email addresses and names are deduplicated
+
+{
+	cat <<-'EOH'
+	# This file lists all individuals having contributed content to the repository.
+	# For how it is generated, see `hack/generate-authors.sh`.
+	EOH
+	echo
+	git log --format='%aN <%aE>' | sort -uf
+} > AUTHORS