BREAKING CHANGE: `Method`, `Request`, `Response`, `StatusCode`,
`Version`, and `Uri` have been replaced with types from the `http`
crate. The `hyper::header` module is gone for now.
Removed `Client::get`, since it needed to construct a `Request<B>`
with an empty body. Just use `Client::request` instead.
Removed `compat` cargo feature, and `compat` related API.
Currently, if the remote closes the connection at the same time that the
pool selects it to use for a new request, the connection may actually
hang. This fix will now more allow the keep-alive read to check the
socket even when the `Conn` think it's busy.
If the connection was closed before the request write happened, returns
back an `Error::Cancel`, letting the user know they could safely retry
it.
Closes#1439
Setting this to false will force HTTP/1 connections to always flatten
all buffers (headers and body) before writing to the transport. The
default is true.
