no longer inheriting from ThreadedSimulation; it works as well as a

Core/Computation/DecoratedLayerComputation.cpp

Core/Computation/DecoratedLayerComputation.h

Core/Computation/RoughMultiLayerComputation.cpp

Core/Computation/RoughMultiLayerComputation.h

Core/Computation/ThreadedComputation.cpp

Core/Computation/ThreadedComputation.h

Core/Multilayer/DecouplingApproximationStrategy.h

Core/Multilayer/SSCApproximationStrategy.h