Add option to create mbox-style output readable by MIME-capable mail readers

[kraken-jim]

Adds support for "--mbox" flag (synonym "-F") which will format the output as an mbox-formatted file, suitable for viewing Base64-encoded or other MIME-enabled messages using mutt or similar mail readers.

[kraken-jim]

Thank you for writing this tool. I just found it recently, and it was very helpful for wading through a large queue of mixed ham and spam.

I wrote this enhancement because many of the messages I looked at were Base64 encoded, or otherwise had significant non-human-readable MIME segments. The modified version can be invoked as smqdecode --mbox > foo to create mbox-formated output. That output can then be read with mutt -R -f foo to decode the Base64 messages and other encodings.

I'm not real fluent in Perl, so please excuse style ugliness or clumsy idioms. I would be grateful to receive your feedback on this patch.

Thanks again for making this tool available to the community.