Change core => src directory for Julia's convention of packages

Project.toml

bench/array_memory_order/access_trajectory.jl

bench/array_memory_order/multiple_dist_lp_view.jl

bench/array_memory_order/multiple_sim.jl

bench/array_memory_order/multiple_sim_view.jl

bench/array_memory_order/read_random_state_trajectory.jl

bench/array_memory_order/read_trajectory.jl

bench/array_memory_order/sim.jl

src/MarkovProcesses.jl

src/_tests_simulate.jl

src/common.jl

src/lha.jl

src/model.jl

src/network_model.jl

src/plots.jl

src/trajectory.jl

src/utils.jl

test/automaton_abc/distributed_R1.jl

...maton_abc/distributed_abc_euclidean_distance_automaton.jl

test/simulation/sim_er_row_buffer_bounded.jl