Glyph filter fixes and test
This corrects a few bugs in vtkPVGlyphFilter :
- A bug with surface extraction where glyph could not be drawn on all surface cells
- A bug when considering volume that can be negative
This adds a test for a specific use case with empty cells.
This also updates VTK to bring last fixes on vtkCellCenters
Edited by Mathieu Westphal (Kitware)