Added finer control on path_alias.

- added a permission to edit path alias.
 - added an admin handler to manage path aliases.
When path alias is changed on node, always keep previous path alias.
  (can be unset from the related admin section).
CMS_API.storage.path_aliases returns the list of path aliases (recents aliases come first).

src/modules/cms_core_module.e

@@ -10,7 +10,8 @@ inherit
 	CMS_MODULE
 		redefine
 			initialize,
-			install
+			install,
+			permissions
 		end
 
 create
@@ -102,6 +103,20 @@ feature -- Router
 		do
 		end
 
+feature -- Security
+
+	permissions: LIST [READABLE_STRING_8]
+			-- List of permission ids, used by this module, and declared.
+		do
+			Result := Precursor
+			Result.force ("install modules")
+			Result.force ("view logs")
+			Result.force ("export core")
+			Result.force ("import core")
+			Result.force ("admin path_alias")
+			Result.force ("edit path_alias")
+		end
+
 note
 	copyright: "2011-2017, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
 	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"