"ergonomic" attachment support

[benjaminweb]

Does rust-imap support message.attachments[i] notation or something similar to work with the attachments of a mail? I could not find anything apart from bodystructure and issue #116.

https://github.com/martinrusev/imbox (Python lib) seems to have an ergonomic user interface.

[jonhoo]

@benjaminweb The crate does as little parsing as it can, limiting itself just to the IMAP standard itself. You'd generally want a higher-level library like mailparse to parse the contents of emails. Now, you may need BODYSTRUCTURE to do so, and there I'm mostly just waiting on tests from @avitex in #134, so that'd be the issue to watch :)