[Haskell-cafe] interfacing TradeKing API

[Donn Cave]

> ... I see that for some reason I modified hoauth Consumer.hs,
> replacing showURL with a path-to-text function I wrote myself, and
> I use my own version of the signRq function from that module that
> returns an unpacked request value.

On further examination, I see I'm using my own version of CurlHttpClient,
where
  - in runClient, if result is not a success code, return (respBody rsp)
    instead of (show errno)
  - add CurlPartialFile to successCodes
  - added (CurlIPResolve 1) to opts to avoid platform IPv6 bug

Then authentication re-evaluates runClient success/error, parsing the
results and potentially turning success into error, and for all errors
makes up a reasonably detailed text rendition.

	Donn