Merge topic 'reslice-iterator'

4cc6d511 Optimize the reslice nearest neighbor interpolation
41fdbbf6 Use logical and in reslice nearest-neighbor path.
24b5ed72 Use vtkImagePointDataIterator in vtkImageReslice

Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Sean McBride <sean@rogue-research.com>
Merge-request: !1709
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