update/cleanup Python dev scripts

- put common code in its own util.py file
- same Python3 shebang for all scripts
- add file docstrings
- fix format string replacement fields in man page template

scripts/util.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+
+import sys
+import os.path
+
+ROOTDIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, os.path.realpath(ROOTDIR))
+
+
+def path(*segments, join=os.path.join):
+    return join(ROOTDIR, *segments)