[mms] IMAP alerts can now be handled by registering an observer with the new Horde_Imap_Client_Base_Alerts object.
Convert IMAP tutorial to Markdown and expand the contents
IMAP alerts now handled in IMP by an observer, rather than a Notification decorator
[mms] Fix deleting multi-level temporary directories in Horde_Util::deleteAtShutdown().
More tweaks to new documentation
[mms] Fix handling mailbox cache data when the mailbox returns NOMODSEQ.