Mark documents as imported and clean them up when closing app, update to DevExpress 21, small tweaks

MultiTool.Form/FormHelpers.vb

@@ -27,4 +27,14 @@ Public Class FormHelper
         MsgBox(oMessage, MsgBoxStyle.Critical, Application.ProductName)
     End Sub
 
+    Public Sub ShowWarning(pMessage As String, Optional pDetails As String = "")
+        Dim oMessage As String = pMessage
+        If pDetails <> String.Empty Then
+            oMessage &= $"{vbNewLine}{pDetails}"
+        End If
+
+        Logger.Info(oMessage)
+        MsgBox(oMessage, MsgBoxStyle.Exclamation, Application.ProductName)
+    End Sub
+
 End Class