Several updates related to STRASSE and quasi free scattering

NPLib/Detectors/GAGG/CMakeLists.txt

NPLib/Detectors/GAGG/TGAGGData.cxx

NPLib/Detectors/GAGG/TGAGGData.h

NPLib/Detectors/GAGG/TGAGGPhysics.cxx

NPLib/Detectors/GAGG/TGAGGPhysics.h

NPLib/Detectors/GAGG/TGAGGSpectra.cxx

NPLib/Detectors/GAGG/TGAGGSpectra.h

NPSimulation/Detectors/GAGG/CMakeLists.txt

NPSimulation/Detectors/GAGG/GAGG.cc

NPSimulation/Detectors/GAGG/GAGG.hh

Projects/GAGG/Analysis.cxx

Projects/GAGG/Analysis.h

Projects/GAGG/CMakeLists.txt

Projects/GAGG/GAGG.detector