Clean up all these Time.at calls

[glacials]

Basically everywhere that uses human-friendly time formats (e.g. HH:MM:SS.NN), which includes the show view and some of the downloadable formats, needs to call something resembling Time.at(some_duration_in_seconds).utc.strftime("%k:%M:%S.%N").strip, which makes for a lot of (sometimes minorly different) identical calls.

We should abstract this to something that we can do things like split.duration.minutes or split.duration.seconds on, or maybe even split.duration.pretty if it turns out that all of the formats expect the same style string.