Convert hook_openid('request', ...) to hook_openid_request_alter()

hook_openid() uses the old pattern, hook_openid($op, $arg), rather than the preferred hook_openid_foo($arg). Perhaps it is better to use drupal_alter() instead. Also, the hook should take the $service array as an argument, because modules may want to inspect $service['types'] like the OpenID module itself does before adding AX to the request.

Would it make sense to also add hooks for the association request in addition to the authentication request?