begin
open override fun beginTravelTo(destination: LocationIfc, purpose: MovePurpose, waiter: ProcessModel.Entity): HoldQueue?(source)
Commands a journey with this transporter's own agent or driver as the waiter.
The wait is always the driving one. A load being carried waits in whatever queue its own protocol suspends it in, and passing it here would attribute its riding time to the space layer instead -- a model that still works while every transport statistic lands in the wrong place.