Added weight into to the CMS_LINK and provide a `sort' feature for CMS_MENU and related.

Protected cms service from registering many time the same module type.
Moved library/persistence/implementation/* under library/persistence/.
Moved site/www/themes to site/themes
For SQLite storage driver, auto create sqlite db file using associated sql script (to be completed).
Added code in demo module to reuse storage for module purpose.
Always call sql_post_execution in sql_query and sql_change, and not anymore by the callers.
Removed is_web and is_html from {CMS_SETUP}, it was not used.
Reused SHARED_*_ENCODER in CMS_ENCODERS
Added CMS_API.logger rather than using directly the SHARED_LOGGER.log ...
Centralize the implementation of current_user in CMS_REQUEST_UTIL
Removed the inheritance on WSF_FILTER for node handlers, since it is useless and unused.
Added CMS_NODE_API and CMS_USER_API
Prefix html id for block generated html items with "block-", to avoid css name conflict on "main", "content" or similar.
Code cleaning

src/modules/cms_module_collection.e

@@ -1,8 +1,8 @@
 note
 	description: "Summary description for {CMS_MODULE_COLLECTION}."
 	author: ""
-	date: "$Date: 2014-11-13 16:23:47 +0100 (jeu., 13 nov. 2014) $"
-	revision: "$Revision: 96085 $"
+	date: "$Date: 2015-02-09 22:29:56 +0100 (lun., 09 févr. 2015) $"
+	revision: "$Revision: 96596 $"
 
 class
 	CMS_MODULE_COLLECTION
@@ -36,6 +36,21 @@ feature -- Status report
 			Result := modules.has (a_module)
 		end
 
+	has_module_with_same_type (a_module: CMS_MODULE): BOOLEAN
+			-- Has module of type `a_type' already inserted?
+		local
+			l_type: TYPE [detachable CMS_MODULE]
+		do
+			l_type := a_module.generating_type
+			across
+				modules as ic
+			until
+				Result
+			loop
+				Result := ic.item = a_module or else ic.item.generating_type = l_type
+			end
+		end
+
 	count: INTEGER
 			-- Number of modules.
 		do
@@ -47,7 +62,9 @@ feature -- Element change
 	extend (a_module: CMS_MODULE)
 			-- Add module
 		do
-			modules.force (a_module)
+			if not has (a_module) then
+				modules.force (a_module)
+			end
 		end
 
 	remove (a_module: CMS_MODULE)