Improve Audible Transits `needs_extrapolation()`

[adam-kosinski]

The better condition of if a track needs to be extrapolated is if the endpoint was a result of the clip or not (or in the 3D space, next to an inaudible point)

[adam-kosinski]

By the way, in the current code link, endpoints significantly outside the active space could be marked as inside and thus needing extrapolation. But this doesn't happen because it's assumed tracks were clipped already. This assumption might be violated in future development.