Adding missing files

src/FiniteDifference/eq_unit_test.hpp

src/FiniteDifference/eq_unit_test_3d.hpp

src/Matrix/SparseMatrix_petsc.hpp

src/Matrix/SparseMatrix_unit_tests.hpp

src/PSE/Kernels_unit_tests.hpp

src/Solvers/petsc_solver.hpp

src/Solvers/umfpack_solver.hpp

src/Vector/Vector_petsc.hpp

src/Vector/Vector_unit_tests.hpp

test/PSE_convergence

...sc_solver<double>_lid_driven_cavity_3d_p1_grid_0_test.vtk

...sc_solver<double>_lid_driven_cavity_3d_p2_grid_0_test.vtk

...sc_solver<double>_lid_driven_cavity_3d_p2_grid_1_test.vtk

...sc_solver<double>_lid_driven_cavity_3d_p3_grid_0_test.vtk

...sc_solver<double>_lid_driven_cavity_3d_p3_grid_1_test.vtk

...sc_solver<double>_lid_driven_cavity_3d_p3_grid_2_test.vtk

...ck_solver<double>_lid_driven_cavity_3d_p1_grid_0_test.vtk

...ck_solver<double>_lid_driven_cavity_3d_p2_grid_0_test.vtk

...ck_solver<double>_lid_driven_cavity_3d_p2_grid_1_test.vtk

...ck_solver<double>_lid_driven_cavity_3d_p3_grid_0_test.vtk