Save quilts via textures, not the render window

This fixes several issues we were encountering when saving quilts (both images and movies) in pure VTK. Previously, quilts were saved using the render window. One problem, though, is that this required resizing the render window to be the quilt size, then temporarily rendering a quilt on it, writing it out, resizing the render window to its original size, and then re-rendering what was previously on it. The resizing of the render window would mark it as modified, which would cause render window interactors to resize it yet again.

Using the textures to save the quilts is a much more straightforward and simple path that does not involve manipulation of the render window. It also does not require any extra rendering, so it is more efficient as well.

Kitware / LookingGlassVTKModule

Save quilts via textures, not the render window #35