Correct parsing of time intervals

Minor change to fix a defect in command line parsing of time intervals with an 's' (seconds) suffix.

Address nagging loss reporting issues with default parameters

This release changes the default time period to 30 seconds, and the default loss interval to 5x of send interval. This should address the nagging low level loss being seen by some.

Support IPv6 scope ids

v1.2

Merge branch 'master' of https://github.com/dennypage/dpinger

Include identifier and destination in log messages for packet related issues

v1.1

Include identifier and dest_str in all icmp packet related logging (f…

First production release

v1.0

Add output identifier