[Eva] Traces domain: improves dot output, fixes oracles

src/libraries/utils/hptmap.ml

src/libraries/utils/hptmap_sig.mli

src/plugins/value/domains/traces/traces_domain.ml

src/plugins/value/value_parameters.ml

src/plugins/value/value_parameters.mli

tests/value/traces/oracle/test1.res.oracle

tests/value/traces/oracle/test2.res.oracle

tests/value/traces/oracle/test3.res.oracle

tests/value/traces/oracle/test4.res.oracle

tests/value/traces/oracle/test5.err.oracle

tests/value/traces/oracle/test5.res.oracle

tests/value/traces/test1.c

tests/value/traces/test2.i

tests/value/traces/test3.i

tests/value/traces/test4.i

tests/value/traces/test5.i