Removes any nesting of polycurves. If this polycurve has just a single segment, the segment is returned.
If, after nest removal, there are adjacent segments which are polylines, they are combined into a single polyline.
The new curve may have a different domain from this polycurve. If the start and end segments of a closed input are polylines,
the result may have a different seam location since the start and end segments will be combined.
RhinoCommon (in RhinoCommon.dll)
Public Function CleanUp As Curve
A new curve that is not necessarily a polycurve if successful, null otherwise.