rm ISimulation::clone, and a number of pointless tests

Core/Fitting/FitObjective.cpp

Core/Simulation/DepthProbeSimulation.cpp

Core/Simulation/DepthProbeSimulation.h

Core/Simulation/GISASSimulation.cpp

Core/Simulation/GISASSimulation.h

Core/Simulation/ISimulation.cpp

Core/Simulation/ISimulation.h

Core/Simulation/ISimulation2D.cpp

Core/Simulation/ISimulation2D.h

Core/Simulation/OffSpecularSimulation.cpp

Core/Simulation/OffSpecularSimulation.h

Core/Simulation/SpecularSimulation.cpp

Core/Simulation/SpecularSimulation.h

Tests/Functional/Core/CoreSpecial/BatchSimulation.cpp

Tests/Functional/Core/CoreSpecial/CMakeLists.txt

Tests/UnitTests/Core/Core/GISASSimulationTest.cpp

Tests/UnitTests/Core/Fresnel/DepthProbeSimulationTest.cpp

Tests/UnitTests/Core/Fresnel/SpecularSimulationTest.cpp

auto/Wrap/doxygenCore.i

auto/Wrap/libBornAgainCore.py