projection on the symmetry boundary condition

src/algebra/EigenvalueSolver.cpp

src/algebra/EigenvalueSolver.hpp

src/language/modules/SchemeModule.cpp

src/language/modules/SchemeModule.hpp

src/mesh/MeshFlatNodeBoundary.cpp

src/scheme/HyperplasticSolverO2.cpp

src/scheme/HyperplasticSolverO2.hpp

src/scheme/PolynomialReconstruction.cpp

tests/test_EigenvalueSolver.cpp