Uses "%ls" if isUTF16Encoded for print/trace

[R32]

resolve #842

class Main {
    static function main() {
        var s = "Akuma 豪鬼";
        trace(s);
        Sys.println(s);
    }
}

output:

src/Main.hx:6: Akuma 豪鬼
Akuma 豪鬼

[sonygod]

Very nice

[sonygod]

@R32 your branch may get some error with emcc target.

#883