ENH: Update selected Filters/General to support DesiredOutputPrecision

This is first of several commits updating filters to support a choice
of desired precision (default, single, or double) for output points. It
uses the analogous code in vtkThreshold as a model.

Change-Id: I7b87d126d9015b8e1ed2ece2368b866147d8c124
Merge topic 'filters-general-desired-output-precision' into master

6025498d ENH: Update selected Filters/General to support DesiredOutputPrecision