Use const and references.

...tions/Utils/MeshEdit/ResetPropertiesInPolygonalRegion.cpp

Applications/Utils/MeshEdit/moveMeshNodes.cpp

Applications/Utils/MeshEdit/removeMeshElements.cpp

GeoLib/MinimalBoundingSphere.cpp

GeoLib/Polygon.cpp

GeoLib/Polygon.h

MathLib/LinAlg/Eigen/EigenLinearSolver.cpp

MathLib/LinAlg/Eigen/EigenLinearSolver.h

MeshGeoToolsLib/GeoMapper.cpp

MeshLib/Mesh.cpp

MeshLib/MeshEditing/FlipElements.cpp

MeshLib/MeshGenerators/MeshGenerator.cpp

MeshLib/MeshGenerators/MeshGenerator.h

ProcessLib/Output.cpp

ProcessLib/Output.h

Tests/GeoLib/TestOctTree.cpp

Tests/GeoLib/TestSurfaceIsPointInSurface.cpp

Tests/MathLib/TestPoint3d.cpp

Tests/MathLib/TestPoint3dWithID.cpp

Tests/MeshLib/TestUniqueMeshId.cpp