[Spambayes] Outlook: new folder selector code

[Mark Hammond]

I have just checked in some significant changes to the "folder selector"
dialog - the cute dialog that presents the list of folders in various parts
of the UI.

Inspired by patches from Tony Meyer, everything should look the same, but
behind the scenes there are 2 major changes that will be of advantage to
Exchange Server users:

* We are back to an extended MAPI (ie, fast) version of the code.  We
believe we have identified and fixed the problem that prevented this code
from working with an Exchange Server before.

* The folder hierarchy is no longer walked fully before the dialog is
created.  The folder hierarchy is only walked as a node is expanded.  This
should make the dialog come up much faster if you have a large "public
folders" hierarchy - these folders are not walked until you actually expand
them (and even then, only walked one level down at that time)

So, in summary, I hope that non Exchange Server users see slight performance
gain displaying this dialog, and Exchange Server users see a significant
one.  Please let me know if you have any problems.

Mark.