imap: command_stats_start call is added for unknown commands. This makes timing shown in reply to unknown commands correct

imap: Fix running time in tagged command replies. The timing information was updated only after command_exec() returned. Most of the commands were handled within a single command_exec() though, so at the time when tagline was sent the running_usecs was still zero. The msecs in ioloop timing was correct though, because it relied only on the command start timing info.

Added imap-hibernate process for gathering IDLEing imap processes. imap_hibernate_timeout setting controls how quickly the connection is moved from imap process to imap-hibernate process. Some IMAP extensions like NOTIFY, SEARCH=CONTEXT and COMPRESS aren't supported yet. There's also a new X-STATE command, which can be used to export the current IMAP connection state to a string and later on imported to get back to the original state (a quick resync feature for IMAP clients). However, this command is disabled for now due to the current code being unoptimized for untrusted input.

imap: Added initial support for METADATA extension. For now this is enabled only when imap_metadata=yes setting is used. The setting will go away once the feature is complete. Also mail_attribute_dict must be set. TODO: - Metadata doesn't work for public namespaces. There should probably be a mail_attribute_public_dict setting for that. - There isn't any kind of quota or other limits - After ENABLE METADATA start sending untagged METADATA entries to clients - /shared/admin should probably return postmaster_address URL - Check if we handle ACLs correctly - RFC says that it SHOULD be possible to set METADATA entries to \NoSelect mailboxes. We probably will never allow this though.

Added support for IMAP URLAUTH and URLAUTH=BINARY extensions Extends imap service with URLAUTH and URLAUTH=BINARY support: - Adds new commands URLFETCH, GENURLAUTH and RESETKEY. Creates imap-urlauth service in src/imap-urlauth. Functionality common to both the imap and imap-urlauth services is located in src/lib-imap-urlauth. TODO: - use mailbox GUIDs instead of names - doveadm command to delete stale urlauth entries? - add delay when attempting to access nonexistent user - create urlauth-worker queue, similar to how indexer-worker works (could we share code?..)

imap: Implemented NOTIFY extension. Requires mailbox_list_index=yes to work (and to show up in capabilities). SubscriptionChange event is still unimplemented.

imap: Updated MOVE implementation.

imap: Implemented MOVE extension.

imap: Added hooks that can be run always before/after any command handler.

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

IMAP: Don't crash if IDLE command is pipelined after a long-running UID FETCH or UID SEARCH. --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