Merge: example: add 24 game task of Rosetta code

Rosetta code example of 24 game
<http://rosettacode.org/wiki/24_game>

Pull-Request: #1372
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Ait younes Mehdi Adel <overpex@gmail.com>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>