Reference for SlicerSPECTRecon automated tests

Zipped file contains reference resources for the automated testing of the SlicerSPECTRecon extension module. The module uses these as benchmarks against the test data provided ("for_slicer_recon") to ensure the accuracy of the module and easily know when things break. Resources include:

i. Reference reconstructed volumes to test the OSEM, OSMAPOSL, BSREM algorithms 

ii. Reference dicom file converted from the simind file of the jazak phantom to test the simind to dicom conversion method

iii. Reference attenuation maps to test attenuation map alignment

iv. Reference scatter data to test the correct loading of the scatter data information.