On timestamps: * - We can't time every field, the protocols don't work like that * - What we want to time is each step of the protocols thus related groups of data * - What we _can_ time is when Go calls our callbacks, which is a close-ish approximation to that, modulo some quirks in the ways it handles various protocols * - Haven't bothered with a Timing{T, time.Time} type for the timed things, because there's only a few of them that are */.