Update dovecot2 to 2.2.24, and bump PORTREVISION on antispam-plugin and
pigeonhole.

• doveconf now warns if it sees a global setting being changed when the same setting was already set inside some filters. (A common mistake has been adding more plugins to a global mail_plugins setting after it was already set inside protocol { .. }, which caused the global setting to be ignored for that protocol.)
• LMTP proxy: Increased default timeout 30s -> 125s. This makes it less likely to reach the timeout and cause duplicate deliveries.
• LMTP and indexer now append ":suffix" to session IDs to make it unique for the specific user's delivery. (Fixes duplicate session ID warnings in stats process.)

+ Added dict-ldap for performing read-only LDAP dict lookups.
+ lazy-expunge: All mails can be saved to a single specified mailbox.
+ mailbox { autoexpunge } supports now wildcards in mailbox names.
+ doveadm HTTP API: Added support for proxy commands
+ imapc: Reconnect when getting disconnected in non-selected state.
+ imapc: Added imapc_features=modseq to access MODSEQs/HIGHESTMODSEQ.

This is especially useful for incremental dsync.

+ doveadm auth/user: Auth lookup performs debug logging if

-o auth_debug=yes is given to doveadm.

+ Added passdb/userdb { auth_verbose=yes|no } setting.
+ Cassandra: Added user, password, num_threads, connect_timeout and

request_timeout settings.

+ doveadm user -e <value>: Print <value> with %variables expanded.

• Huge header lines could have caused Dovecot to use too much memory (depending on config and used IMAP commands). (Typically this would result in only the single user's process dying with out of memory due to reaching service { vsz_limit } - not a global DoS).
• dsync: Detect and handle invalid/stale -s state string better.
• dsync: Fixed crash caused by specific mailbox renames
• auth: Auth cache is now disabled passwd-file. It was unnecessary and it broke %variables in extra fields.
• fts-tika: Don't crash if it returns 500 error
• dict-redis: Fixed timeout handling
• SEARCH INTHREAD was crashing
• stats: Only a single fifo_listeners was supported, making it impossible to use both auth_stats=yes and mail stats plugin.
• SSL errors were logged in separate "Stacked error" log lines instead of as part of the disconnection reason.
• MIME body parser didn't handle properly when a child MIME part's --boundary had the same prefix as the parent.