consolidate _fuzzy_group_* into fuzzy_group with sane kwords

I've spent a fair amount of time thinking about this. I wrote the _fuzzy_group versions and their keyword takes a boolean but you have to read the docstring to figure our what the function does. I'm trying now to get a universal API to run them that is clearer. I'm open to suggestions but the self-documenting nature of these is the best I've come up with so far. Because really, this is the only question one has when picking one of the functions. The critical idea for which keywords are needed are:

- what is the trump value (False or None) which, when seen, allows a short circuit and whose value is returned immediately? `trump=None or False` or `trump_is_None = True or False`
- should two non-trump values behave like a trump? `double_jeopardy=True or False`

Can we just make the PR change but keep fuzzy_group private until we settle on a better scheme?