This will be a literal rewrite of the legacy Perl code responsible for processing udev net events into config file entries (interface -> hw-id). The goals are:

1. Drop legacy Perl code, and notably, the use of XorpConfigParser; the latter has been removed but for these remaining scripts.
2. Provide a base line for investigation of the issue of unexpected interface reordering (T3871), and a wrapper within which to test solutions.
3. Keep the rewrite as conservative as possible, as it should act as a transition to an interface-monitor daemon (2), and soon be replaced.