HTML link regex
// use url group and ignore case (because of something like HREF)
// based on http://regexlib.com/REDetails.aspx?regexp_id=1048
// based on http://regexlib.com/REDetails.aspx?regexp_id=1048
href="(?(((ht|f)tp(s?))\://)?((([a-zA-Z0-9_\-]{2,}\.)+[a-zA-Z]{2,})|((?:(?:25[0-5]|2[0-4]\d|[01]\d\d|\d?\d)(?(\.?\d)\.)){4}))(:[a-zA-Z0-9]+)?(/[a-zA-Z0-9\-\._\?\,\'/\\\+&%\$#\=~]*)?) "