Segment Seat Availability
 [x] No overlap when segments only touch at handoff
 [x] No overlap adjacent legs
 [x] Overlap when inner segment inside outer
 [x] Overlap when longer segment contains shorter
 [x] No overlap when only share drop of first with pick of second
 [x] Unknown stops do not overlap
 [x] Resolve booking segment prefers ticket pick drop
 [x] Parse stoppage trims and filters
 [x] No overlap when later leg starts where earlier booking ends
 [x] Overlap when existing booking stored with reversed pick drop
 [x] Overlap for nested segment on same route
 [x] Path overlap cairo sharm blocks ras sudr to el tor
 [x] Path no overlap cairo ras sudr vs ras sudr to el tor

