Merge pull request #14 from jwuttke/iss1603

Core/Computation/DecoratedLayerComputation.cpp

Core/Computation/DecoratedLayerComputation.h

Core/Computation/MainComputation.cpp

Core/Computation/ProgressHandler.cpp

Core/Computation/ProgressHandler.h

Core/Computation/RoughMultiLayerComputation.cpp

Core/Computation/RoughMultiLayerComputation.h

Core/Computation/SpecularComputation.cpp

Core/Computation/ThreadedComputation.cpp

Core/Computation/ThreadedComputation.h

Core/Simulation/Simulation.cpp

GUI/coregui/Models/JobWorker.cpp

GUI/coregui/mainwindow/mainwindow.cpp