New tests for util: credit, is_divisible, value_in.
New tests for util: credit, is_divisible, value_in.

F483/counterparty-lib,tokenly/counterparty-lib,monaparty/counterparty-lib,jarymoth/counterpartyd,CounterpartyXCP/counterparty-lib,stefcrypto/counterparty-lib,F483/counterparty-lib,monaparty/counterparty-lib,gotcha/testcounter,coinwarp/dogeparty-lib,CounterpartyXCP/counterparty-lib