Invalid error notification for multiple emails

When entering multiple email addresses in the send to a friend page, if the person puts both a comma AND a newline, this causes an invalid notification of email address which is missing.

This is caused by a problem with the conversion of end of lines into commas. (print_mail.inc, line 180)

  // All new-lines are replaced by commas
  $to_addrs = str_replace(array("\r\n", "\n", "\r"), ',', $form_state['values']['txt_to_addrs']);
  // Create an array from the string
  $to_array = explode(',', $to_addrs);

If this is changed instead to

  // All new-lines are replaced by commas
  $to_addrs = preg_replace("/(\r\n|\n|\r|,)+/", ",", $form_state['values']['txt_to_addrs']);
  // Create an array from the string
  $to_array = explode(',', $to_addrs);

multiple commas, newlines or other user entry problems are handled in a cleaner fashion.

It also then matches the description underneath the form entry textarea.