Add the use of a mask image in ImageFusionByInjection
Add PandoraBoxReconstructionFilters::ConvertSliceStackTo3DImage
Add PandoraBoxReconstructionFilters::Project3DImageToSliceStack
Add a simple 3D Gaussian based version to compute PSF.

void PandoraBoxReconstructionFilters::ComputePSFImage
Add observation model (y=Hx) in PandoraBoxReconstructionFilters

ComputerObservationModelParameters
SimulateObservations
Use float instead of double to reduce memory use in ComputerObservationModelParameters and SimulateObservations
Add Convert3DImageToVNLVector into PandoraBoxReconstructionFilters
Add ConvertVNLVectorToSliceStack in PandoraBoxReconstructionFilters
Add ConvertVNLVectorTo3DImage and IterativeBackProjection in PandoraBoxReconstructionFilters
Add ConvertParametersToRigidMatrix and ConvertRigidMatrixToParameters in PandoraBoxReconstructionFilters