tracks_within should handle multiple passes through study area #12
Description
To avoid making a spectrogram without big gaps of NaN values, GPS points need to be fairly close together... so they are "densified" between successive points with linear (and circular) interpolation. However, the main use case also involves constraining them to the proximity of a study area.
Sometimes (especially at airstrips like Kantishna, Ruth Glacier, INR, etc) aircraft will depart and then return with the same flight_id - and tracks_within faces a big disjunction in time between points. In the best case scenario this will (1) slow down model runs, and (2) dilute time-dependent metrics like Percentile Leq, 1s and Percent Time Above. In a worst-case scenario, the airplane will (3) jump from perimeter point (x_t, y_t) to perimeter point (x_t+n, y_t+n) such that the resulting "imaginary" segment intersects the study area. In this case, even solely energy-based metrics (maximum LAeq, 1s) are contaminated.
Most solutions are awkward, so I'm just marking this as a bug for now. At the very least, densification over a certain time step should be eliminated!