Added a potentialMap method that takes an implicit EquiSets that seems to work nicely. I think I'll change
plain old map, flatMap, etc., to this. Only thing is I don't think I can ... well I suppose I could
get a SortedEquiSets output with a dependent type.
Dropped one of each of the overloaded *Into methods.
Dropped the collectInto, mapInto, and flatMapInto methods and relevant test
code. Added a comment about how can't take an EquiSets implicitly because flatMap
needs the path to use in the function. So I think the into(...) syntax plus
the map, flatMap, and collect, etc., methods that take the same type T as
the output type of the function is the best we can do.