#2 Add minimal PING and ARP capabilities into SDIG

[Jim Klimov]

Sometimes the SDIG command is run on a UNIX host attached to the same network that a target host is connected to. At times this UNIX machine is *the* network router, and may not have SNMP for any number of reasons.
A new feature that I'm proposing is to:
1) include local host ARP table inspection in order to find MAC address of the target IP, and
2) include a (command-line optional) step of "pinging" the target host a few times (regardless of which network it is on, and whether it responds to ICMP) in order to refresh the ARP and CAM tables of hosts and switches along the path.
These steps are more or less done in my CGI wrappers, but a more proper place for them is the SDIG binary itself.
I believe code may be borrowed from *BSD or Linux sources for "ping" and "arp" commands, etc. Perhaps consult with OpenSolaris source to ensure operation under *Solaris as well.
I have not yet started working on the code, and I am not sure when/if I will start on it, so if anyone beats me to it - thanks! ;)