When ordered compositing is enabled, ParaView determines the process order by
partitioning the data using PKdTree. However, in some cases, like when volume
rendering image-data, we need to override the partitioning using the partitions
from the image data itself. This commit cleans up the API for proving such
information to the view from a representation. In past it was tightly coupled
with vtkImageData producer. This change makes it possible to just pass the
meta-data about extent-translator to use, origin, spacing, extents etc. to
generate the partitioning. This will make it possible for non-image data
representations to provide this meta-data without having to create a
vtkImageData.

This removes obsolete vtkBSPCutsGenerator. Also vtkKdTreeManager now always
regenerates the KdTree. The checks to avoid regenerating unless the input
changed have been removed.

Change-Id: I469f54ba931fd64f66097d0ea579e9d8652d9bfc