make ospray pass create the scene graph so user doesn't have to
move ospray specific controls to ivars on ospraynodes
Improve caching
Now we cache what we can but not so much that we
fail time, or dynamic, or actor hiding. Also prevent double
delete on actor hiding and style
no special access just for ospray
Access to scenegraph view node would probably be OK.
make sure we get cell colors right for arbitrary polygons
using a reverse index from triangulated (or cylindered or pointed)
output cell back to input vtk cell. The output cells are homogenous
but the input cells aren't necessarily.
quad 0 -> tri 0 : rindex 0
          tri 1 : rindex 0
tri 1  -> tri 2 : rindex 0
color 0 -> color 0,1
color 1 -> color 2
flesh out point size and line width controls
Now user chosen pointsize and linewidth on mapper matter.
Also, user can designate a point aligned array to vary elements individually
and user can provide a lookuptable to manipulate those values arbitrarily.
In al...