ENH: Make IntialMoving and InitialFixed transforms decorated inputs

This enhances the ability to change multiple registrations together.

Change-Id: Id88f479df3c13e4193d8d5ce049f6651d1400c3f
ENH: Update SimpleRegistration test

This is using the latest best practices for the ImageRegistrationMethodv4.

1) InPlace input, instead of modifying output.
2) Using GetTransform, to get the output object of the filter
3) Connecting multiple registrations together with a pipeline
4) Correcting the call back to print at each initialization of a level

Change-Id: I92f208e55adf795de110f90a591c616621b14d81
BUG: Don't create new Decorator in GenerateData

Use the Decorator already created and set the output transform to be
held by the existing container. This allows the output DataObject to
be connected to the next filter, and reused. If the output DataObject
is changed then pipeline connection is broken.
Merge topic 'ImageRegistrationMethodv4PipelineInputs'

ff88bf33 BUG: Don't create new Decorator in GenerateData
99fc98f8 ENH: Update SimpleRegistration test
965331d0 ENH: Make IntialMoving and InitialFixed transforms decorated inputs
STYLE: Remove unnecessary comments.

Change-Id: I70c5152252264b68ed9d5a8dbaa0675a6d20a73f
Merge topic 'ImageRegistrationMethodv4PipelineInputsRmCmt'

7634bc82 STYLE: Remove unnecessary comments.