[vtkusers] a bug in vtkFollower

[Matjaz Subelj]

I believe there is a bug in vtkFollower since the 1.33 revision (6
months ago).
Someone reported it before but it didn't get fixed (it's a trivial one
though).
>From the changelog (diff to previous 1.32):

"ENH: now vtkFollower exhibits special behavior for ParallelProjection
     (i.e. follows VPN instead of actor -> camera vec if
ParallelProjection)"

This is okay if it would be true. It follows DOP instead. Since DOP =
-VPN
the actor gets mirrored (Direction Of Projection vs. View Plane Normal). 
You can see this effect if you enable parallel projection in
textOrigin.tcl 
example in graphics directory.

Matjaz