Do not use else after return. (#1821)

Applications/Utils/MeshEdit/editMaterialID.cpp

MaterialLib/Adsorption/Reaction.cpp

MaterialLib/Fluid/Density/CreateFluidDensityModel.cpp

.../RelativePermeability/CreateRelativePermeabilityModel.cpp

MeshLib/MeshEditing/DuplicateMeshComponents.cpp

MeshLib/MeshEditing/MeshRevision.cpp

NumLib/ODESolver/TimeDiscretizationBuilder.cpp

ProcessLib/Parameter/Parameter.cpp