Add testing for proper image size after stride indexing
Add testing for proper image size after stride indexing

This add testing for the image slicing being smaller than that of
numpy. The issue was raised on ITK Discourse:
https://discourse.itk.org/t/image-slicing-in-python/2160

The test added includes the example provided on Discourse.

InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,SimpleITK/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,InsightSoftwareConsortium/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,richardbeare/SimpleITK,blowekamp/SimpleITK,blowekamp/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,richardbeare/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,blowekamp/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,blowekamp/SimpleITK,blowekamp/SimpleITK,SimpleITK/SimpleITK