Add mbox support

[ket000]

Add mbox support to read /var/mail/root File on Linux servers. This will be useful to replace mailx command.

[soywod]

Yes, I would like Himalaya to support mbox. We need a pimalaya/io-mbox lib to interact with mbox files, and support streaming because mbox archive can be really fat.

[ket000]

May be you can borrow code from : https://github.com/dcarrero/mboxshell

For now this works perfectly fine. Single binary and tui fits the bill.

[soywod]

Thanks for sharing, looks impressive what they did. I will definitely check the parser. As soon as we define a mbox backend, the whole Pimalaya suite will benefit from it: CLI, TUI, sync, watch changes (not so useful for mbox tho…).