Added function to clear custom form elements

inabox.wpf/DigitalForms/Designer/DynamicFormDesignGrid.cs

@@ -319,6 +319,12 @@ namespace InABox.DynamicGrid
             }
         }
 
+        public void ClearElementTypesAndActions()
+        {
+            _elements.Clear();
+            _elementActions.Clear();
+        }
+
         public void AddElementType<TElement>(string caption, string category, bool allowduplicate = false, bool visible = true)
             where TElement : DFLayoutElement
         {