Engine.

 *  **OkHttp now does cookies.** We've replaced `java.net.CookieHandler` with
    a new interface, `CookieJar` and added our own `Cookie` model class. This
    new cookie follows the latest RFC and supports the same cookie attributes
    as modern web browsers.

 *  **Form and Multipart bodies are now modeled.** We've replaced the opaque
    `FormEncodingBuilder` with the more powerful `FormBody` and

 *
 * Neither of the built-in URL models offer direct access to path segments or query parameters.
 * Manually using `StringBuilder` to assemble these components is cumbersome: do '+' characters get
 * silently replaced with spaces? If a query parameter contains a '&', does that get escaped?
 * By offering methods to read and write individual query parameters directly, application
 * developers are saved from the hassles of encoding and decoding.