Message store events notification

[Sébastien Michel]

Hi all,

progress is being made in the rewrite of our code toward the master branch.
I pushed an update in our github repository, below the changelog :

1) adding the support of these event types:
- MessageAppend
- MessageExpire

2) adding the support of these event parameters:
- MessageNew and MessageAppend may now include flagNames event parameter
- vnd.cmu.MessageCopy now includes oldMailboxID and vnd.cmu.oldUidset
event parameters

3) code refactoring:
- simplify event list handling with a chained list
- simplify the aborting of event

4) improvement:
- adding an helper to check for the required parameters for each type of event.
- ipurge, cyr_expire and cyr_virusscan now support event notification
- JSON as event notification format. (eg:
{"event":"MessageAppend","timestamp":"2011-09-20T08:21:37.384Z","mailboxID":"imap://domain.tld/user.test1;UIDVALIDITY=1316506897/;UID=2","messages":2,"vnd.cmu.newmessages":1,"uidnext":3,"vnd.cmu.midset":"<30968696.41188060100410@domain.tld>","flagNames":"\seen"}
- implementing the behavior of event_exclude_folder setting to turn
off notification that occur on a given list of
folder (may use SPECIAL-USE in the future)

I rebased the msgevent branch on current master :
https://github.com/worldline-messaging/cyrus-imapd/tree/msgevent

my todo list is updated :
- support more event types and event parameters : QuotaExceed,
QuotaWithin, QuotaChange, Login, Logout, MailboxSubscribe,
MailboxUnSubscribe
- the ability to turn on and off groups of related events
- the ability to turn off notification for SPAM => depends on SPECIAL-USE
- format the IMAP URL with the external representation of the mailbox
- documentation (where and which format ?)

any comments or suggestions are welcome.

Thanks,

Sébastien

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