Added notion of "front" page.

Changed CMS_HOOK_BLOCK.get_block_view to accept only attached string for `a_block_id'.
Keep simple name in CMS_MENU_SYSTEM.
Module that implements a CMS_HOOK need now to redefine CMS_MODULE.register_hooks .
Added simple code for NODE_MODULE, in order to see something.
Added CMS_URL_UTILITIES that should be used to compute url for cms path such as "/foo/bar".
Implemented get_active in CMS_RESPONSE to update the "is_active" on each link.
Added NOT_IMPLEMENTED_ERROR_CMS_RESPONSE.
Implemented a few hooks in DEMO module, for testing.
Updated smarty template related code.

cms/src/modules/basic_auth/basic_auth_module.e

@@ -70,10 +70,4 @@ feature {NONE} -- Implementation: routes
 			a_router.handle_with_request_methods ("/basic_auth_logoff", l_bal_handler, l_methods)
 		end
 
-feature -- Hooks
-
-	register_hooks (a_response: CMS_RESPONSE)
-		do
-		end
-
 end