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.