Extended filter to support culling unused points.

Previously the filter just passed points through. This behavior is an
option now (PassPointsOn) and instead unused points (after extraction) are
discarded. This implementation is consistent with vtkExtractGeometry and
is the new default behavior (PassPointsOff).

Change-Id: I8fb396caa236e54c0afdb69f94a0ea785e8bca97
Merge topic '0014457-ExtractPolyData-PassPoints' into master

0567a19c Extended filter to support culling unused points.