Modal and AOT exit dialog

[Takuma Murakami]

Harold,

> I just checked in a framework for you to display the number of connected 
> clients in the Exit box.  All that is left for you to do is to go to 
> windialogs.c/winExitDlgProc/WM_INITDIALOG and set the value to 
> iConnectedClients to whatever the number of connected clients is.  :)

Thank you for the great help, I utilized the framework with
a slight change that took iConnectedClients into ScreenPriv.
(A file scope variable could be preferable since it is referenced
only within windialog.c.)

I also added the silent exit feature (actually the above feature
is a by-product of this).  If a user adds the line (just 1 word)
SilentExit
the Exit dialog won't appear when no client is connected.
Of course, this is off by default not to confuse users.

The single word preference is the easiest to implement with
lexer and parser, but you might want to change it to more
readable ones such as "SilentExit = yes" before the release.

Takuma Murakami