Redesigned hooks system (moving from CMS_RESPONSE to CMS_API).

Indeed, hooks does not require RESPONSE interface,
   and should be setup before, at the system level (i.e CMS_API)
Added exportation solution via CMS_HOOK_EXPORT.
Updated blocks settings for demo example project.

src/hooks/export/cms_hook_export.e

@@ -0,0 +1,31 @@
+note
+	description: "[
+			CMS HOOK providing a way to export module data according to specific export parameters.
+		]"
+	date: "$Date$"
+	revision: "$Revision$"
+
+deferred class
+	CMS_HOOK_EXPORT
+
+inherit
+	CMS_HOOK
+
+feature -- Hook	
+
+	export_to (a_export_id_list: detachable ITERABLE [READABLE_STRING_GENERAL]; a_export_parameters: CMS_EXPORT_PARAMETERS; a_response: CMS_RESPONSE)
+			-- Export data identified by `a_export_id_list',
+			-- or export all data if `a_export_id_list' is Void.
+		deferred
+		end
+
+--	export_identifiers: detachable ITERABLE [READABLE_STRING_32]
+--			-- Optional list of exportation ids, if any.
+--		do
+--				-- To redefine if needed.
+--		end
+
+note
+	copyright: "2011-2015, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
+	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
+end