Fixed InitialFolder so it now works more than first time its called pr. application

The dialog.SetDefaultFolder(item) is only set first time the applications sets the folder,
Next time the folder will be restored to last picked object and the 'Default folder' is ignored
Use instead dialog.SetFolder which behaviour better matches the name 'InitialFolder'

Author: buildcomplete

src/Ookii.Dialogs.Wpf/VistaFileDialog.cs

@@ -647,7 +647,11 @@ internal virtual void SetDialogProperties(Ookii.Dialogs.Wpf.Interop.IFileDialog
             if( !string.IsNullOrEmpty(_initialDirectory) )
             {
                 Ookii.Dialogs.Wpf.Interop.IShellItem item = NativeMethods.CreateItemFromParsingName(_initialDirectory);
-                dialog.SetDefaultFolder(item);
+                
+                // The dialog.SetDefaultFolder(item) is only set first time the applications sets the folder,
+                // Next time the folder will be restored to last picked object and the 'Default folder' is ignored
+                // Use instead dialog.SetFolder which behaviour better matches the name 'InitialFolder'
+                dialog.SetFolder(item);
             }
 
             if( !string.IsNullOrEmpty(_title) )