Fixed checkoff logic so that it handles Signoff style of checkoffs

The checkoff/signoff list was not always refreshing in the step properties panel.
Added format flag CheckoffOnSubStepsOnly for Bryon and Braidwood

PROMS/VEPROMS.CSLA.Library/Format/PlantFormat.cs

@@ -1250,6 +1250,15 @@ namespace VEPROMS.CSLA.Library
 				return LazyLoad(ref _SkipSpaces, "@SkipSpaces");
 			}
 		}
+		// put in for Bryon and Braidwood
+		private LazyLoad<bool> _CheckoffOnSubStepsOnly;
+		public bool CheckoffOnSubStepsOnly
+		{
+			get
+			{
+				return LazyLoad(ref _CheckoffOnSubStepsOnly, "@CheckoffOnSubStepsOnly");
+			}
+		}
 	}
 	#endregion
 	//#region RightCheckOffBox