Changelog for req-0.4.0

Req 0.4.0

Added the Req monad and runReq function to run it. This allows to use req without defining new (orphan) instances.

Made URL parsing functions parseUrlHttp and parseUrlHttps recognize port numbers.
Added req' function that allows to perform requests via a callback that receives pre-constructed request and manager.
Removed the ReturnRequest HTTP response implementation as it was not quite safe and was not going to work with retrying. Use req' instead for “pure” testing.
Changed the type of httpConfigCheckResponse, so the second argument can be any instance of HttpResponse.
Added built-in automatic retrying. See httpConfigRetryPolicy and httpConfigRetryJudge in HttpConfig. The default configuration retries 5 times on request timeouts.
Added the makeResponseBodyPreview method to the HttpResponse type class that allows to specify how to build a “preview” of response body for inclusion into exceptions.
Improved wording in the documentation and README.md.

Added support for multipart form data in form of ReqBodyMultipart body option and reqBodyMultipart helper function. This also required a change in type signature of getRequestContentType, which now takes body, not Proxy body because we need to extract boundary from body and put it into Content-Type header. This change, however, shouldn't be too dangerous for end-users.
Added support for OAuth 1.0 authentication via oAuth1 option.