dogtail: Fix test_timeline.py:TimelineTest.test_multiple_drag
dogtail: Fix test_timeline.py:TimelineTest.test_split
dogtail: Update timeline tests to use the new getTimelineX/Y methods
dogtail: Fix first half of test_timeline.py:TimelineTest.test_ripple_roll
dogtail: Fix and update test_timeline.py:TimelineTest.test_ripple_roll_image_video_mix to detect properly the video sample
dogtail: Look for timecode_widget in TimelineTest.setUp