check_fping

Features / Improvements

- Includes the code from fping (in a modified state) instead of calling it and parsing the output.

- Takes care of 'Unable to parse ping output' and such.

- Fixes the 1 second maximum threshold value in check_fping, which was hardcoded in the fping source.

- Removes the ridiculous appearance of precision down to a millionth of a millisecond (0.1000000 RTA), and instead gives proper and valuable output in a sensible manner.

- Both check_ping and check_fping command line syntax works just fine, so it could be used to replace either one (-n and -p both denote number of packets to send).

Drawbacks:

Requires root privileges for raw sockets (if run setsuid it drops
privileges again after obtaining the socket). This is common to all ping programs though.

ToDo:
Parallellize packet sending. This requires a different packet identity encoding algorithm, as well as some manner of delay so that hosts don't think they're being flooded, so I'll wait a while with this.