Drop the “Sigma_e” statement

doc/manual/source/the-model-file.rst

preprocessor

tests/ecb/SUR/panel_var_diff_NB_simulation_test.mod

tests/ecb/SUR/panel_var_diff_NB_simulation_zero_eq.mod

tests/ecb/SUR/sur_noniterative.mod

tests/ecb/SUR/sur_params_noniterative.mod

tests/ecb/pooled_fgls/panel_var_diff_NB_simulation_test.mod

tests/ecb/pooled_fgls/test_param_names.mod

tests/ecb/pooled_ols/panel_var_diff_NB_simulation_test.mod

tests/ecb/pooled_ols/test_param_names.mod

tests/t_lag2.mod

tests/t_periods.mod