ENH: tubeImageToTubeRigidRegistration CLI skeleton.
ENH: Flesh out tubeImageToTubeRigidRegistration CLI.

Based off ImageToTubeRigidRegistrationTest.
ENH: Add regression comparison for itkImageToTubeRigidRegistrationTest.
ENH: itkImageToTubeRigidRegistration: remove unused MaskImage member.
ENH: itkImageToTubeRigidRegistration: remove unused.

IterationCommand.  GetCenterOfRotation.
ENH: itkImageToTubeRigidRegistration: Set good default scales in constructor.
ENH: itkImageToTubeRigidRegistration: remove SparseRegistration method.

This was unused.  It was just doing a dense search of a hard coded parameter
domain instead of sparse registration.
ENH: itkImageToTubeRigidRegistration.h changes from "2" to "".
ENH: itkImageToTubeRigidRegistration.txx changes from "2" to "".
ENH: Cleanup from itkImageToTubeRigidMetric readthrough.
ENH: Remove unused code in itkImageToTubeRigidMetric.

Related to "m_T".
ENH: itkImageToTubeRigidMetric: fix use of offsets.

There were some hacks to avoid const of GetDerivative.
ENH: Verbose to itkDebugMacro.
STYLE: Throw exception instead of printing to std::cout.
ENH: Base/Registration build and pass tests with ITKv4.
COMP: Fix iterator warnings.
ENH: itkImageToTubeRigidMetric remove unused member.
ENH: itkImageToTubeRigidMetric: remove unused.
ENH: itkImageToTubeRigidMetric cleanup.

Removed unused methods.

Fix const correctness with m_Scale.

Use typedefs.
DOC: Document itkImageToTubeRigidMetric Sampling.