Add simpler helper script to generate MD5 and SHA checksum files

.. which we use before manually publishing to Maven Central.

Author: tnull

scripts/generate_checksum_files.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+md5sum $1 | cut -d ' ' -f 1 > $1.md5
+sha1sum $1 | cut -d ' ' -f 1 > $1.sha1
+sha256sum $1 | cut -d ' ' -f 1 > $1.sha256
+sha512sum $1 | cut -d ' ' -f 1 > $1.sha512