Temporary solution until the Overlord is an ItkFilter

directly an itkImage.
This is useful for bypassing the itkpipeline mechanism. (As for
elastixfilter currently). If the itkpipeline is bypassed, the (update)
control flow must be handed over to the Overlord. This is done via the
AfterRegistration mechanism in Overlord.

ENH: reorganized Sink and Souce file structure

Containers

added RunRegistrationInterface

And added Fixed/Moving image interfaces

ComponentSelector

The ItkSmoothingRecursiveGaussianImageFilterComponent is templated over
the dimensionality and pixeltype of in- and output. Stings "Dimensionality" and
"PixelType" are added as Criteria to select the right Component.

- Automatically write pixel type and dimension to parameter file from
image type at runtime
- Default parameter maps
- Lots of fixes

Blueprint::ParameterMapType

and cxx files