Drop repetitive -address from parameter names
Add --reply-to option to run-command-notify
Make mandatory command line arguments positional

Subject and sender must always be set, so make them positional
arguments.

The destination address(es) (--to) is/are also mandatory, but there can
be many of those. For now that remains an explicit option.
Split __main__
Add option to always send notification e-mail
Rename run-and-notify script
Give examples descriptive file names

Closes #2.