[geary] (16 commits) ...Merge branch 'wip/789924-network-transition'. Fixes Bug 789924.

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  abcc296... Remove tabs from source code. (*)
  54194ad... Ensure only one ConnectivityManager instance is used per en (*)
  be8d8be... Start/stop outbox as the SMTP host becomes reachable/unreac (*)
  ef8b3cf... Reorganise and clean up SmtpOutboxFolder code. (*)
  3fb7237... Make SmtpOutboxFolder postman more robust. (*)
  b5b0ad9... Minor deserialiser debug logging tidy up. (*)
  ba5ae1f... Ensure IMAP client sessions are closed when going offline. (*)
  575d3f1... Only attempt to obtain an ImapClientSession when some are a (*)
  f64a203... Minor SmtpOutboxFolder cleanup. (*)
  acb339f... Misc ClientSessionManager fixes. (*)
  4218dbb... Fix race between account becoming ready and MinimalFolder o (*)
  2a0cfc3... Don't delay opening remote folder when it is being waited o (*)
  ef25806... Trigger account synchronizer when account becomes ready. (*)
  f273058... Rely on the ready signal to re-open folder IMAP connections (*)
  304fa9d... Add a IMAP pool stop timeout as well as a start to help pre (*)
  fddf609... Merge branch 'wip/789924-network-transition'. Fixes Bug 789

(*) This commit already existed in another branch; no separate mail sent