make field.name.replace('_', '-') optional

[martinResearch]

in some case we want to keep the underscode in the argument names, it would be great to have a boolean argument added to _add_dataclass_options to allow that

[jcal-15]

If no one else is planning on working on this, I can implement it.

[mivade]

Closed by #64. Thanks, @jcal-15!