Changing vcluster initialization

src/FiniteDifference/FDScheme.hpp

src/FiniteDifference/eq_unit_test.hpp

src/FiniteDifference/eq_unit_test_3d.hpp

src/Matrix/SparseMatrix_Eigen.hpp

src/Matrix/SparseMatrix_unit_tests.hpp

src/PSE/Kernels_unit_tests.hpp

src/Solvers/umfpack_solver.hpp

src/Vector/Vector_eigen.hpp

src/Vector/Vector_unit_tests.hpp

src/unit_test_init_cleanup.hpp