rename k2 to moment_of_inertia_factor

src/MINT/MINT_load_MS_grid.c

src/MINT/MINT_mix_stars.c

src/MINT/MINT_stellar_structure_CHeB.c

src/MINT/MINT_stellar_structure_MS.c

src/RLOF/RLOF_dynamical_comenv.c

src/binary_c_macros.h

src/binary_c_parameters.h

src/binary_c_structures.h

src/binary_star_functions/calculate_spins.c

src/binary_star_functions/contact_system.c

src/binary_star_functions/prevent_overspin.c

src/common_envelope/common_envelope_event_handler.c

src/common_envelope/common_envelope_evolution.h

src/common_envelope/common_envelope_evolution_BSE.c

src/evolution/initialize_parameters.c

src/logging/log_every_timestep.c

src/logging/show_derivatives.c

src/rotation/breakup_angular_momentum.c

src/rotation/core_moment_of_inertia.c

src/rotation/envelope_moment_of_inertia.c