Uninitialized values (and ITK setters) in `otb::ImageToGenericRSOutputParameters`

Description

When itkSetMacro() is used with member-data left uninitialized in their constructors, quality related tools will emit error/warning messages.

Steps to reproduce

It's for instance the case for valgrind that'll barks things like

==26964== Conditional jump or move depends on uninitialised value(s)
==26964==    at 0x34B56F4D: operator!= (itkSize.h:145)
==26964==    by 0x34B56F4D: SetOutputSize (otbImageToGenericRSOutputParameters.h:106)
==26964==    by 0x34B56F4D: otb::ImageToGenericRSOutputParameters<otb::VectorImage<float, 2u> >::EstimateOutputSize() (otbImageToGenericRSOutputParameters.hxx:249)
==26964==    by 0x34B5CAE4: otb::ImageToGenericRSOutputParameters<otb::VectorImage<float, 2u> >::Compute() (otbImageToGenericRSOutputParameters.hxx:66)
==26964==    by 0x34B5D137: otb::Wrapper::OrthoRectification::DoUpdateParameters() (otbOrthoRectification.cxx:285)
==26964==    by 0x2D034A93: otb::Wrapper::Application::UpdateParameters() (otbWrapperApplication.cxx:490)

Proposed resolution

I've identified the issue in otb::ImageToGenericRSOutputParameters class, where it could be fixed with

PointType                        m_OutputOrigin{0.0};
SpacingType                      m_OutputSpacing{0.0};
SizeType                         m_OutputSize{0, 0};

(IMO, the easiest is to use C++11 member initialization given we have these setters; and unfortunately ITK constructors prevents zero-initialisation with empty braces.)

I haven't checked whether it happens elsewhere.