Add the ability to customize or hide system messages on account creation.

Currently, the messages are hardcoded and cannot be customized or removed. I the case of having a custom "thank for registering" page, these messages can become redundant. It would be ideal if we had some more flexibility about this.

// Compose the appropriate user message--admin approvals don't require a validation email.
  if($reg_pass_set && variable_get('user_register', 1) == 1) {
    if ($pre_auth) {
      $message = t('A validation e-mail has been sent to your e-mail address. In order to gain full access to the site, you will need to follow the instructions in that message.');
    }
    else {
      $message = '';
    }
  } else {
    $message = t('Your password and further instructions have been sent to your e-mail address.');
  }