merge latest commit

diff --cc src/prolog/lib/clpb.pl
Simple merge

diff --cc src/prolog/machine/attributed_variables.rs
Simple merge

diff --cc src/prolog/machine/compile.rs
Simple merge

diff --cc src/prolog/machine/machine_state.rs
Simple merge

diff --cc src/prolog/machine/machine_state_impl.rs
Simple merge

diff --cc src/prolog/machine/mod.rs
Simple merge

diff --cc src/prolog/machine/system_calls.rs
Simple merge