Improved sorting options

[ghost]

(feel free to rename to fit description:) Option to sort messages in inbox by more than to,from,subject,received. Ideas:

• "Status" : read/unread (or just "Read" ?)
• "Tag" : This would involve a side idea, the ability to search by tags and tag messages
• "BM id" : if there's one central inbox (seen in issues), it would be smart to provide an sort option to highlight/show/sort IDs (like "Account" in Thunderbird).

Optional: ability to write custom sort-rule and apply them to inbox(es).

[mailchuck]

Good idea.