Moved implementation of the specular magnetic implementation

Core/Computation/SpecularComputationTerm.cpp

Core/Multilayer/MatrixFresnelMap.cpp

Core/Multilayer/SpecularMagneticOldStrategy.cpp

Core/Multilayer/SpecularMagneticOldStrategy.h

Core/Multilayer/SpecularMagneticStrategy.cpp

Core/Multilayer/SpecularMagneticStrategy.h

Tests/UnitTests/Core/Fresnel/SpecularMagneticTest.cpp

Tests/UnitTests/Core/Fresnel/SpecularMagneticTest_v2.cpp