Added support for path_aliases.

Refactored CMS_MODULE.router (..): WSF_ROUTER design,
  to create only one router object of type CMS_ROUTER.
Added optional CMS_NODE.link: CMS_LOCAL_LINK
Reviewed permissions related to node module.
Refactor and add CMS_STORAGE_SQL(_BUILDER) abstractions
   for implementation relying only on SQL statements.
Factorized sql builder initialization (to work for sqlite and mysql storage builders).
Added CMS_RESPONSE.formatted_string (a_text: READABLE_STRING_GENERAL; args: TUPLE): STRING_32
Added function "translation", but not implemented for now.
Updated indexing notes and comments.
Code cleaning.

modules/node/persistence/cms_node_storage_i.e

@@ -107,6 +107,8 @@ feature -- Change: Node
 			no_id: not a_node.has_id
 			valid_user: attached a_node.author as l_author and then l_author.id > 0
 		deferred
+		ensure
+			has_id: a_node.has_id
 		end
 
 	update_node (a_node: CMS_NODE)