There is some ambiguity about the need for two separate modules
in the ITK/Modules/Compatibility organization.

All classes and features in ITK/Modules/Compatibility are
considered as Legacy code, and will be removed from the toolkit
in future releases.

Deprecated:  Any code that provides a feature or function
             that is no longer supported in ITKv4

V3Compatibility: This is a place for code where the feature is
                 still supported in ITKv4, but the API has changed
                 this layer allows for easier transition to ITKv4
                 by providing access to the ITKv3 API.
