Returns a ContourMeasure for the first contour in the path. A contour is a
sequence of path segments starting at a moveTo and ending before the next
moveTo (or end of path). Use the next property on the returned
ContourMeasure to iterate through subsequent contours. Returns nil if the
path has no contours.
local contour = pathData:contours()while contour do print(contour.length) contour = contour.nextend