timeline-object: Properly reflect contained TrackObject duration and inpoint properties changes
timeline-object: Properly reflect contained TrackObject duration and inpoint properties changes

cfoch/ges,cfoch/gst-editing-services,cfoch/ges,cfoch/gst-editing-services,pitivi/gst-editing-services,cfoch/ges,pitivi/gst-editing-services,volodymyrrudyi/gst-editing-services,pitivi/gst-editing-services,pitivi/gst-editing-services,cfoch/ges,cfoch/gst-editing-services,volodymyrrudyi/gst-editing-services,volodymyrrudyi/gst-editing-services,cfoch/gst-editing-services