Fix test.

tests/arab_to_roman.aer

@@ -2,7 +2,7 @@ class Program {
 
 	private function num2Roman(int $num) {
 		int $n = intval($num);
-		int $result = '';
+		string $result = '';
 		mixed $lookup = array('M' => 1000, 'CM' => 900, 'D' => 500, 'CD' => 400,
 			'C' => 100, 'XC' => 90, 'L' => 50, 'XL' => 40,
 			'X' => 10, 'IX' => 9, 'V' => 5, 'IV' => 4, 'I' => 1);