This entails the addition of various methods and iterator types where
appropriate, based on what’s on `HashMap`, though I doubt that people
will actually be able to make all that much use of the iterators. They’d
be of more use with a basis of a trait other than `Any`, such as might
be conveniently achieved by combining this with my MOPA crate.
(Getting a little close to HKT there, innit?)
You know, I wonder sometimes if anyone ever reads these messages after
they are written, myself included. If you have read this, please drop me
a note; I’m curious.
I’ve also gone over all the stability attributes, marking things as
appropriate.