ENH: WBIRDemoTest
ENH: transformix writes deformation field
ENH: itkv4 registration runs 3 levels (hard coded)
ENH: itkv4 exposes forward deformationfield (still with some workarounds)
ENH: itkv4 exposes transformed moving image (still with some workarounds)
BUG: itkv4 MeanSquares Component initiated wrong Metric