add delete filter support

scripts/tutorials/entity_edit_filters/prevent-erase-in-zone-example.js

@@ -0,0 +1,24 @@
+//
+// prevent-erase-in-zone-example.js
+// 
+//
+// Created by Brad Hefta-Gaub to use Entities on Jan. 25, 2018
+// Copyright 2018 High Fidelity, Inc.
+//
+// This sample entity edit filter script will keep prevent any entity inside the zone from being erased.
+//
+// Distributed under the Apache License, Version 2.0.
+// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+function filter(properties, type, originalProperties, zoneProperties) {    
+
+    if (type == Entities.ERASE_FILTER_TYPE) {
+        return false;
+    }
+    return properties;
+}
+
+filter.wantsOriginalProperties = true;
+filter.wantsZoneProperties = true;
+filter;