Added the missing copy and move constructor for the string class
Added the missing copy and move constructor for the string class

sjinks/PHP-CPP,CopernicaMarketingSoftware/PHP-CPP,sjinks/PHP-CPP,sjinks/PHP-CPP,CopernicaMarketingSoftware/PHP-CPP,sjinks/PHP-CPP,dreamsxin/PHP-CPP,dreamsxin/PHP-CPP