dynamic checks for arg types?

[dckc]

If the API is going to dynamically check args, let's (a) do it everywhere and (b) unit test it. But I'd be surprised if it's cost-effective.

see https://github.com/crypto-coder/rchain-api/commit/761190475b63b90e46ee8eac576c899207c9bbd1#diff-c2c91badddf4395b9125973b96d00ee7R196

previously: https://github.com/rchain/rchain-api/issues/24