Add diffstat output
Add an output that indicates the difference between the currently measured metrics and the last ones. E.g.:
[target_01 on box]
Alive: 3/4 (-1/0)
Execs: 84 m (+2 m)
Speed: 737.0 x/s (+30.2 x/s)
Pend: 0/0 (-10/-1)
Crashes: 12 (+5)