fapi_validation_rule_url falsely accepts unencoded unicode characters for absolute URLs

Function fapi_validation_rule_url is faulty. It accepts absolute URLs which contain unencoded unicode characters. This differs from Drupals common.inc: valid_url() which handles them correctly (per RFC 3986).

To repeat the problem, validate absolute URL string such as:
http://drupal.org/ö
fapi_validation_rule_url() returns true
valid_url() returns false, which is correct.

fapi_validation_rule_url() was changed in commit http://cgit.drupalcode.org/fapi_validation/commit/?id=b26a6cd
to use it's own regex instead of calling Drupal's valid_url() for absolute URLs.