dns_timeout and dns_retransmit_interval in ms

Convert dns_timeout and dns_retransmit_interval configuration options to
use millisecond resolution.

One second resolution is too coarse for small timeouts in
delay-sensitive environments, especially when a retransmit, bypass, or
another corrective action is available and is likely to produce a
positive outcome. In DNS world specifically, most timeouts are measured
in milliseconds.

NOTE: This patch add a new cf.data.pre type the time_msec which is a
uint64_t. I found more practical to use an integer to store miliseconds,
but using the timeval type may has advandages too.

This is a Measurement Factory project