Display label over image when not at the same resolution

[aylward]

Would be nice (particularly for deep learning notebooks that typically generate output images at a lower resolution than the input image) to be able to show a label over an image even when the label is at a different (lower) resolution than the image.

[rijobro]

also possible mismatches in image extents and affine transformation matrices would be ideal.

[thewtex]

:+1:

[bnmajor]

Closing as resolved in Kitware/itk-vtk-viewer#629