add a new modified sandbox "box" The original file was pulled from moe (git://git.ucw.cz/moe.git) by Martin Mares's commit on Sun Jul 29 23:53:56 2012 +0200 The modification is to make it separately compilable and add more option to specify additional argument to the program. (Please see usage guide) run `gcc -o box -std=c99 box64-new.c` to compile.