`swadm link history` could report better timestamps for link events

[bnaecker]

swadm link history is a really helpful subcommand that prints the history of events in the link state machines. Today, it shows those with timestamps as "milliseconds in the past". It would be great to add a flag controlling this output format, such as a human-friendly duration (say 1h 4m) or as an absolute timestamp (though that might be difficult to interpret if NTP hasn't synced yet).

[Nieuwejaar]

Agreed. This irritates me each time I use the command, and whoever wrote it this way deserves a strong talking to.

Because we have all the timestamps as deltas from "now", we can easily print time-of-day stamps that make sense relative to the sled's notion of "now". Those timestamps should also correlate to the timestamps in the log files - unless we crossed an NTP sync boundary during a link's history. Anyway, it certainly can't hurt to make that available, as long as we don't make it the default.