Provide statistics for ping responses

[fhunleth]

fping has a particularly nice summary. Here's an example:

$ fping -s -C 3 8.8.8.8
8.8.8.8 : [0], 84 bytes, 6.46 ms (6.46 avg, 0% loss)
8.8.8.8 : [1], 84 bytes, 9.67 ms (8.06 avg, 0% loss)
8.8.8.8 : [2], 84 bytes, 12.9 ms (9.68 avg, 0% loss)
8.8.8.8 : 6.46 9.67 12.92
       1 targets
       1 alive
       0 unreachable
       0 unknown addresses
       0 timeouts (waiting for response)
       3 ICMP Echos sent
       3 ICMP Echo Replies received
       0 other ICMP received
 6.46 ms (min round trip time)
 9.68 ms (avg round trip time)
 12.9 ms (max round trip time)
        2.015 sec (elapsed real time)