Move the system related function to new System_API module.
Fix bug: temp file are not re-initialized when process is killed due to timeout or memory usage

 runtime -t 1   -p TIME 1 2 -p MESSAGE hello world -u TIMExMESSAGE --
   "sleep TIME && echo MESSAGE"
...

-> mv: cannot /tmp/runtime_tmp_GV_: No such file or directory
Fstat
Add 'last_run' link at the end of the experiments; add terminaison time.