Added a module that allows the output to be sampled. With the new -q option, the user is now able to decide whether the output should be sampled as follows: Only every nth query is output and only responses that correspond to one of these sampled queries will be output.
e.g.:
dnscap -r ./file.pcap -g -q 10 will output only every 10th query and these queries' corresponding responses.

Updated dnscap.1.in to match the Sampling Module addition

uthash is used as the hash table library in the Sampling Module

Added a module that allows the output to be sampled. With the new -q option, the user is now able to decide whether the output should be sampled as follows: Only every nth query is output and only responses that correspond to one of these sampled queries will be output.
e.g.:
dnscap -r ./file.pcap -g -q 10 will output only every 10th query and these queries' corresponding responses.

Changed parameter for the q option from "unsigned int" to "nth"

changed the parameter of the q option from "unsigned int" to "nth"

Applied most of the suggested corrections suggested by jelu

Disabled the sampling code if dnscap is not compiled with libbind.

Corrected chooseSidesResponse logic.

Added a proper way to support ipv6 addresses for sampling.

Fixed the libbind dependency logic for sampling

Updated the support for ipv4/v6 in the sampling code.
Also made some slight changes to the libbind dependency logic.

rephrased a comment from "Sampling Module" to "sampling"