HTTP request pipeline suitable for use across multiple go-routines

 Package autorest implements an HTTP request pipeline suitable for use across
 multiple go-routines and provides the shared routines relied on by AutoRest
 (see https://github.com/Azure/autorest/) generated Go code.
 .
 The package breaks sending and responding to HTTP requests into three phases:
 Preparing, Sending, and Responding.
 .
 Each phase relies on decorators to modify and / or manage processing.
 Decorators may first modify and then pass the data along, pass the data first
 and then modify the result, or wrap themselves around passing the data (such as
 a logger might do). Decorators run in the order provided.
 .
 Preparers and Responders may be shared and re-used (assuming the underlying
 decorators support sharing and re-use). Performant use is obtained by creating
 one or more Preparers and Responders shared among multiple go-routines, and a
 single Sender shared among multiple sending go-routines, all bound together by
 means of input / output channels.
 .
 Decorators hold their passed state within a closure (such as the path
 components in the example above). Be careful to share Preparers and Responders
 only in a context where such held state applies. For example, it may not make
 sense to share a Preparer that applies a query string from a fixed set of
 values. Similarly, sharing a Responder that reads the response body into a
 passed struct (e.g., ByUnmarshallingJson) is likely incorrect.
 .
 Lastly, the Swagger specification (https://swagger.io) that drives AutoRest
 (https://github.com/Azure/autorest/) precisely defines two date forms: date and
 date-time. The github.com/Azure/go-autorest/autorest/date package provides
 time.Time derivations to ensure correct parsing and formatting.
 .
 Errors raised by autorest objects and methods will conform to the
 autorest.Error interface.