Removed outdated override of ClearItems()

With the underlying `ClearItems()` now calling `Remove()` and, thus, `RemoveItem()` (abfe213), it's no longer necessary to override `ClearItems()` to remove the `IncomingRelationships`, as this is already being done by `RemoveItem()`.

Author: JeremyCaney

OnTopic/Associations/TopicReferenceCollection.cs

@@ -135,25 +135,5 @@ protected override sealed void RemoveItem(int index) {
 
     }
 
-    /*==========================================================================================================================
-    | OVERRIDE: CLEAR ITEMS
-    \-------------------------------------------------------------------------------------------------------------------------*/
-    /// <inheritdoc/>
-    protected override sealed void ClearItems() {
-
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Handle recipricol references
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      foreach (var item in Items) {
-        item.Value?.IncomingRelationships.Remove(item.Key, AssociatedTopic, true);
-      }
-
-      /*------------------------------------------------------------------------------------------------------------------------
-      | Provide base logic
-      \-----------------------------------------------------------------------------------------------------------------------*/
-      base.ClearItems();
-
-    }
-
   } //Class
 } //Namespace