Adding segmentation overview notebook.
Adding segmentation overview notebook.

Notebook was originally used for the SPIE'16 tutorial.

InsightSoftwareConsortium/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,zivy/SimpleITK-Notebooks,InsightSoftwareConsortium/SimpleITK-Notebooks