imap: Add imap_client_command_get_reason() All the command -> reason string conversions now go through this function.

global: Add mailbox_transaction_set_reason() calls Added to the most important places.

imap: Share mailbox closing code in SELECT/UNSELECT/CLOSE/LOGOUT/deinit

imap: Added client_disconnect_if_inconsistent() to remove code duplication. Based on patch by Stephan Bosch

imap: If SELECT fails with "mailbox is inconsistent", disconnect client. (Plus related cleanups.) The inconsistency can also be used to indicate that something is badly wrong and nothing useful can be done before client reconnects.

imap: Send * OK [CLOSED] always before tagged SELECT reply.

Moved mailbox_equals() to lib-storage.

Marked functions parameters that are allowed to be NULL. Some APIs were also changed. The non-obvious APIs where NULL parameter was changed to "" are master_service_init() and auth_master_user_list_init(). These checks can currently be enabled only on a patched clang: http://llvm.org/bugs/show_bug.cgi?id=6786

lib-storage: mailbox_alloc() now takes a virtual mailbox name and other related API changes. All storage_name <-> vname conversions now go through the same two mailbox_list methods. This has many benefits, such as: * listescape plugin is now much simpler and bugfree * allows changing lib-storage API to use UTF-8 mailbox names in future * allows creation of "mailbox aliases" plugin

imap: Avoid using mailbox_list_get_mailbox_name_status() The validity checks should already be done by the actual commands in most cases (if they didn't, there would be race condition bugs). The only exception is SUBSCRIBE. It doesn't require that the mailbox exists, but we want to enforce that anyway via IMAP.

imap: Some mailbox accessing commands failed with wrong error message. --HG-- branch : HEAD

Fixed creating mailboxes over \noselect mailboxes. --HG-- branch : HEAD

mailbox_list_get_mailbox_name_status() now separates between existing mailbox and dir. --HG-- branch : HEAD

imap: Don't send NONEXISTENT resp code to non-delete operations. --HG-- branch : HEAD

Allow namespace prefix to be opened as mailbox, if it already exists. --HG-- branch : HEAD

IMAP: Send [ALREADYEXISTS], [NONEXISTENT] and [TRYCREATE] resp-codes correctly. --HG-- branch : HEAD

Initial commit for making mail_storage:mailbox_list to be from 1:1 to n:n. This will allow namespaces to share the same storage and a single namespace to have multiple storages (multiple mailbox formats). Neither works currently, and this commit probably breaks some things. --HG-- branch : HEAD

Renamed headers to prevent collision if they were flattened on an install. --HG-- branch : HEAD