method_of_moments: use underscore instead of camel case for variables

matlab/+mom/Jtest.m

matlab/+mom/default_option_mom_values.m

matlab/+mom/get_data_moments.m

matlab/+mom/matched_irfs_blocks.m

matlab/+mom/matched_moments_block.m

matlab/+mom/mode_compute_irf_matching.m

matlab/+mom/objective_function.m

matlab/+mom/optimal_weighting_matrix.m

matlab/+mom/print_info_on_estimation_settings.m

matlab/+mom/run.m

matlab/+mom/standard_errors.m