WIP: Update more Filters/Core to support DesiredOutputPrecision

This updates a second batch of core 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.

Unit tests for these filters are work in progress.

Change-Id: I404c1bf2ea624e9065768297a1ec5247d1751647