Provide the real mailbox information for title data for special mailboxes
Correctly label fake element
Fix mailbox display labels

Only special mailboxes have translated labels. Submailboxes don't.

i.e. if the Drafts mailbox is A, A.B is not displayed as Drafts.B

I'm not sure why we ever did it this way, but this makes absolutely no
sense in the folder list display.  Especially since we don't allow
children of special mailboxes (in the display), so there's no benefit in
labeling them this way.

This fixes a bunch of display issues with submailboxes of special
mailboxes.