Update my show to utilize IPN 2 widgets
Update my show to utilize IPN 2 widgets

The new myshow adds a ipython notebook slider widget for 3d images.

TODO: detect if ipython version is new enough to have widgets.

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