Refactored add child feature, to have all the page specific code in CMS_PAGE_NODE_TYPE_WEBFORM_MANAGER (and not in the general node code).

Note that ideally PAGE could be a separated page node module (as it is for blog).
Added listing of children for each "page".

modules/node/persistence/cms_node_storage_null.e

@@ -86,6 +86,13 @@ feature -- Access: node
 			create {ARRAYED_LIST [CMS_USER]} Result.make (0)
 		end
 
+feature -- Access: outline		
+
+	children (a_node: CMS_NODE): detachable LIST [CMS_NODE]
+			-- <Precursor>
+		do
+		end
+
 	available_parents_for_node (a_node: CMS_NODE): LIST [CMS_NODE]
 			-- <Precursor>
 		do