cleaned up gauss_seidel; results dont match master
cleaned up assemble_div_u; results dont match master
cleaned up assemble_grad_p; results dont match master
cleaned up build_diagonal_of_Ahat; results dont match master
cleaned up assemble_dAhatp_entry; results dont match master
Changed E->P to be 0-based; results dont match master
cleaned up solve_Ahat_p_fhat_CG; results match master for incompressible case don't match for compressible
cleaned up global_div_norm2; all results match master branch