Reorganized code
Code cleanup
Replaced sqrt() with vcl_sqrt() to deal with compilation problems associated with Visual Studio.
FIX: typos
Bug fixes for itk::SparseImage.
Fixed bugs in peak detection algorithm and Utils.h.
Replaced vnl_random with itk::MersenneTwisterRandomVariateGenerator (suited for Monte-Carlo simulations).
Replaced std::map with std::tr1::unordered_map in itk::SparseImageContainer for speedup.
Added itk::SparseVectorImageNearestNeighborInterpolateImageFunction.h.
Added masking capability to itk::WarpedDWIFromBasisWeightsImageFilter.
Code is now ITK-4.3.1 compatible.
ENH: Added itk::SparseVectorImage class. Modified SparseToVectorImageConverter to use this class.
ENH: SphericalFunctionFromBasisWeightsConverter now uses itk::SparseVectorImage.
ENH: Added VectorToSparseImageConverter.
BUG: Fixed spacing issue in itk::SparseVectorImageFileWriter.
ENH: Sparse image readers/writers now use ITKSYS.
BUG: Fixed pathname issues in sparse image readers and writers.
BUG: Fixed pathname issues in sparse image readers and writers.
Renamed itk::SparseVector*ImageInterpolateImageFunction as         itk::SparseImage*InterpolateImageFunction
Added interpolation image function for itk::SparseVectorImage Updated WarpedDWIFromBasisWeightsGenerator Fixed a bug in itkSparseVectorImage.h