BUG: The vtkTubeFilter assumed data had no verts.

The vtkTubeFilter assumed that the cellId of the first line was
zero, but that is not true if there are any verts in the data set.
The result was that cell scalars were not properly copied from
the input to the output.

Change-Id: Ib62e2080ffe69d3241eb5f43c58ff1ea09e08a39
Merge topic 'tubefilter-cellId-bug' into master

01b4db05 BUG: The vtkTubeFilter assumed data had no verts.