COMP: Fixed itkGradientDescentOptimizerv4 wrapping warnings

I splitted the 3 wrapping calls in 3 separate files and fixed the wrapping.

The warnings :
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(5): Unknown type type: itk::GradientDescentOptimizerBasev4 [typedef]
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(5): Unknown type type: itk::GradientDescentOptimizerv4 [typedef]
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(5): Unknown type type: itk::ObjectToObjectOptimizerBase [typedef]
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(4): ITK type not wrapped, or currently not known: itk::GradientDescentOptimizerBasev4Template< double >
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(4): ITK type not wrapped, or currently not known: itk::GradientDescentOptimizerv4Template< double >
/home/kevin/kitware/ITK_Build/Wrapping/Modules/ITKOptimizersv4/itkGradientDescentOptimizerv4.xml: warning(4): ITK type not wrapped, or currently not known: itk::ObjectToObjectOptimizerBaseTemplate< double >

Should also hopefully fix the new error on the dashboard I introduced by fixing the itkQuasiNewtonOptimizerv4 warnings (http://review.source.kitware.com/#/c/14317/)
/home/kevin/kitware/ITK_Build/Wrapping/Typedefs/itkQuasiNewtonOptimizerv4.i:87: Warning 401: Nothing known about base class 'itk::GradientDescentOptimizerv4Template< float >'. Ignored.
/home/kevin/kitware/ITK_Build/Wrapping/Typedefs/itkQuasiNewtonOptimizerv4.i:87: Warning 401: Maybe you forgot to instantiate 'itk::GradientDescentOptimizerv4Template< float >' using %template.

Change-Id: I15b6af11690ed6efeaced68f73af5212ab5dc364
Merge topic 'fix-itkGradientDescentOptimizerv4-warnings2'

faa279d1 COMP: Fixed itkGradientDescentOptimizerv4 wrapping warnings