Revisited the persistence layer.

Simplified schema to focus on user and node.
Now possible to have sqlite via ODBC and/or mysql support, and select using configuration file.
Updated demo example.

library/src/persistence/cms_storage.e

@@ -0,0 +1,47 @@
+
+note
+	description : "[ 
+				CMS interface to storage
+			]"
+	date: "$Date: 2015-01-27 19:15:02 +0100 (mar., 27 janv. 2015) $"
+	revision: "$Revision: 96542 $"
+
+deferred class
+	CMS_STORAGE
+
+inherit
+	CMS_USER_STORAGE
+
+	CMS_NODE_STORAGE
+
+	SHARED_LOGGER
+
+feature {NONE} -- Initialization
+
+	initialize
+		do
+		end
+
+feature -- Error Handling
+
+	error_handler: ERROR_HANDLER
+			-- Error handler.
+
+feature -- Misc
+
+--	set_custom_value (a_name: READABLE_STRING_8; a_value: attached like custom_value; a_type: READABLE_STRING_8)
+--			-- Save data `a_name:a_value' for type `a_type'
+--		deferred
+--		end
+
+--	custom_value (a_name: READABLE_STRING_8; a_type: READABLE_STRING_8): detachable TABLE_ITERABLE [READABLE_STRING_8, STRING_8]
+--			-- Data for name `a_name' and type `a_type'.
+--		deferred
+--		end
+
+--	custom_value_names_where (a_where_key, a_where_value: READABLE_STRING_8; a_type: READABLE_STRING_8): detachable LIST [READABLE_STRING_8]
+--			-- Names where custom value has item `a_where_key' same as `a_where_value' for  type `a_type'.
+--		deferred
+--		end
+
+end