vtkLocationSelector can return more than one point when selecting the nearest point

The search process in vtkLocationSelector::vtkInternalsForPoints::Execute() is faulty. Each point in the dataset is checked to see if it is within a distance epsilon of the location of interest. If epsilon is large enough, all points in the data set will be selected. We want only the one that is closest to the given location, so the search process needs to be fixed.