C2021-004 logic to maintain table shading information

PROMS/Volian.Controls.Library/StepRTB.cs

@@ -2579,6 +2579,7 @@ namespace Volian.Controls.Library
 							if (!myGrid.SelectNextCell())
 							{
 								myGrid.MyBorders.InsertRow(myGrid.Rows.Count - 1);
+								myGrid.MyShading.InsertRow(myGrid.Rows.Count - 1); // C2021-004 Table Cell Shading information
 								myGrid.Rows.Add(1);
 								myGrid.SelectNextCell();
 							}