We don't currently need a couple of the key manipulation features
that we have, since we aren't yet doing relays or onion service
clients.
Part of #125
Instead of putting a fully qualified name in the text, in most cases
we should just use the short name of the type or function we're
referring to.
In other words, instead of saying [`crate::module::Foo`], we should
typically say [`Foo`](crate::module::Foo).
I tried using -Z minimal-versions to downgrade all first-level
dependencies to their oldest permitted versions, and found that we
were apparently depending on newer features of all three crates.
I'm kind of surprised there were only three.
eta
Nick Mathewson
Jani Monoses
Daniel Eades