Misspelled variable name

[ovidius72]

The file src/RRule.php, on line 660

static public function parseRfcString($string)
	{
		trigger_error('parseRfcString() is deprecated - use new RRule(), RRule::createFromRfcString() or \RRule\RfcParser::parseRRule() if necessary',E_USER_DEPRECATED);
		return RfcParser::parseRRule($sring);
	}

is returning a misspelled $sring variable instead of $string, that causes an error on parsing the provided text.

[rlanvin]

Thanks!