Option for removing sliced3VWR gradient background

[GoogleCodeExporter]

To generate figures for presentations and publications, a "switch leet
gradient background off" switch would be nice.

Hack to switch off:
obj._background_renderer.RemoveAllViewProps()
obj._background_renderer.SetBackground(1, 1, 1)

(vtk_kit.utils has the code to setup the background renderer)

Original issue reported on code.google.com by cpbotha on 17 Jun 2008 at 11:13