v3.0: IMAP hierarchy flexibility

[Thomas Jarosch]

Hi Bron,

given the switch to UUIDs for the folder structure in the backend of v3.0*, 
I'm wondering if the following folder structure can be supported:

- Inbox/folder_below_inbox
- folder_next_to_inbox
- user/smith/other_shared_folder


Background info: Some users want to create folders below inbox
and folders next to inbox. "altnamespace" is a workaround in that direction.
Microsoft Exchange and Dovecot support this feature and that's
why management keeps nagging me.

Cheers,
Thomas

*) no more getting paged at 3am in the morning because of folder renames.