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/configuration/cms_setup.e

@@ -1,7 +1,7 @@
 note
 	description: "Class that enable to set basic configuration, application layout, core modules and  themes."
-	date: "$Date: 2015-01-27 19:15:02 +0100 (mar., 27 janv. 2015) $"
-	revision: "$Revision: 96542 $"
+	date: "$Date: 2015-02-13 13:08:13 +0100 (ven., 13 févr. 2015) $"
+	revision: "$Revision: 96616 $"
 
 deferred class
 	CMS_SETUP
@@ -14,16 +14,6 @@ feature -- Access
 	layout: CMS_LAYOUT
 			-- CMS layout.
 
-	is_html: BOOLEAN
-			--  api with progressive enhancements css and js, server side rendering.
-		deferred
-		end
-
-	is_web: BOOLEAN
-			-- web: Web Site with progressive enhancements css and js and Ajax calls.
-		deferred
-		end
-
 	enabled_modules: CMS_MODULE_COLLECTION
 			-- List of enabled modules.
 		local
@@ -42,7 +32,7 @@ feature -- Access
 			only_enabled_modules: across Result as ic all ic.item.is_enabled end
 		end
 
-feature {CMS_MODULE} -- Restricted access
+feature {CMS_MODULE, CMS_API} -- Restricted access
 
 	modules: CMS_MODULE_COLLECTION
 			-- List of available modules.
@@ -129,13 +119,10 @@ feature -- Access: storage
 					attached storage_drivers.item (l_database_config.driver) as l_builder
 				then
 					Result := l_builder.storage (Current)
-				else
-					create {CMS_STORAGE_NULL} Result
 				end
 			else
 				to_implement ("Workaround code, persistence layer does not implement yet this kind of error handling.")
 					-- error hanling.
-				create {CMS_STORAGE_NULL} Result
 				create l_message.make (1024)
 				if attached ((create {EXCEPTION_MANAGER}).last_exception) as l_exception then
 					if attached l_exception.description as l_description then
@@ -161,11 +148,24 @@ feature -- Access: storage
 
 feature -- Element change
 
+	module_registered (m: CMS_MODULE): BOOLEAN
+		do
+			Result := modules.has (m)
+		end
+
+	module_with_same_type_registered (m: CMS_MODULE): BOOLEAN
+		do
+			Result := modules.has_module_with_same_type (m)
+		end
+
 	register_module (m: CMS_MODULE)
 			-- Add module `m' to `modules'
+		require
+			module_not_registered: not module_registered (m)
+			no_module_with_same_type_registered: not module_with_same_type_registered (m)
 		deferred
 		ensure
-			module_added: modules.has (m)
+			module_registered: module_registered (m)
 		end
 
 end