Extending license to 2021

...im/AtmosphericRayTracing/EigenraySearch/AdaptiveRayGrid.h

...Sim/AtmosphericRayTracing/EigenraySearch/EigenrayEngine.h

...m/AtmosphericRayTracing/EigenraySearch/EigenraySettings.h

...gationPathSim/AtmosphericRayTracing/ODESolver/ODESolver.h

...ude/ITAPropagationPathSim/AtmosphericRayTracing/RayGrid.h

include/ITAPropagationPathSim/AtmosphericRayTracing/Rays.h

...ationPathSim/AtmosphericRayTracing/Simulation/ARTEngine.h

...ionPathSim/AtmosphericRayTracing/Simulation/ARTSettings.h

...athSim/AtmosphericRayTracing/Utils/RayToPropagationPath.h

include/ITAPropagationPathSim/BaseEngine/BaseDiffraction.h

include/ITAPropagationPathSim/BaseEngine/BaseImageSource.h

include/ITAPropagationPathSim/ConvexDiffraction/Engine.h

include/ITAPropagationPathSim/Definitions.h

include/ITAPropagationPathSim/MirrorImage/Engine.h

include/ITAPropagationPathSim/UrbanEngine/UrbanDiffraction.h

include/ITAPropagationPathSim/UrbanEngine/UrbanImageSource.h

...tionPathSim/AtmosphericRayTracing/EigenraySearch/Worker.h

...PathSim/AtmosphericRayTracing/Simulation/AdaptiveSolver.h

...osphericRayTracing/EigenraySearch/AdaptiveRayGridTest.cpp

...mosphericRayTracing/EigenraySearch/EigenrayEngineTest.cpp