Remove positional parameters in Member instantiation

[briangerard]

The positional parameters to Member's init are long and ugly. As @aschrab suggested in his comment on #7, we should either instantiate using a dict, or create it empty and populate it field-by-field. I'm leaning toward the latter approach at present, but we'll see after some code.

[briangerard]

These changes are on the simplify_member branch.

So far, it's testing well. The code looks a good bit cleaner, and feels a lot less fragile.

So far there's some unit testing in place, and I've done some testing in my home environment. I want to give it another once-over before putting in a pull request or merging.