Implementation of IMAP IDLE

- Use a newer version of imaplib
 - Hijack the keepalive process to send IDLE instead of NOOP

offlineimap.conf

@@ -307,6 +307,19 @@ remoteuser = username
 #
 # reference = Mail
 
+# In between synchronisations, OfflineIMAP can monitor mailboxes for new
+# messages using the IDLE command. If you want to enable this, specify here
+# the folders you wish to monitor. Note that the IMAP protocol requires a
+# separate connection for each folder monitored in this way, so setting
+# this option will force settings for:
+#     maxconnections - to be at least the number of folders you give
+#     holdconnectionopen - to be true
+#     keepalive - to be 29 minutes unless you specify otherwise
+# This option should return a Python list. For example
+#
+# idlefolders = ['INBOX', 'INBOX.Alerts']
+#
+
 # OfflineIMAP can use multiple connections to the server in order
 # to perform multiple synchronization actions simultaneously.
 # This may place a higher burden on the server.  In most cases,