I modified the polyline to ribbon filter to clean the polydata since
the vtkRibbonFilter can't handle duplicate points. I also corrected
several bugs with the integral curver filter with the generation of 
normals for displaying the curves as ribbons. This resoles #2700.



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@29478 18c085ea-50e0-402c-830e-de6fd14e8384