Special handling of `--help` and `--version`

The two options have special behavior:

- they're baked in OptParse; preferrably, they shouldn't (this can be handled by manually raising an error)
- `--help` should disregard the correctness of the rest of the option/arguments when present. it's unclear how to handle broken options, since they would cause an error to be raised (check if optparse does an exception in this case)