error: Strip trailing whitespace in module docstring

Signed-off-by: W. Trevor King <wking@tremily.us>
main: Add an explicit --version argument.

Use an explicit `version` action instead of the undocumented (and
deprecated) `version` keyword to ArgumentParser [1,2].

[1]: http://docs.python.org/3.3/library/argparse.html#action
[2]: http://docs.python.org/3.3/library/argparse.html#upgrading-optparse-code

Signed-off-by: W. Trevor King <wking@tremily.us>
version: Add get_versions and teach rss2email --full-version

This makes it easier for users to submit useful bug reports.

Signed-off-by: W. Trevor King <wking@tremily.us>
main: Add missing `# Copyright` tag for update-copyright.py

Signed-off-by: W. Trevor King <wking@tremily.us>
Ran update-copyright.py

Signed-off-by: W. Trevor King <wking@tremily.us>