clojure.walk/keywordize-keys and stringify-keys should not turn Records into maps

With this change:

user=> (stringify-keys {:a 1 :b 2})
{:a 1, :b 2, "a" 1, "b" 2}

So there would need to be a dissoc applied as well. One issue there is that dissoc on Records, when dissocing keys that are components of the Record, also returns a map instead of the Record.

The proposed patch seems like it has other consequences for non-records. For example, sorted maps would retain their sortedness whereas they do not currently. That may or may not be desirable, but it's certainly a much broader change in behavior than that implied by the ticket.

Does the change in stringify-keys even work? Doesn't seem like it when eyeballing it and causes test failures when applied.