* Removed unnecessary classes, among which `BatchMode`, `CloseStatus`, etc.
* Coalesced all listener interfaces into `Session.Listener`.
* Moved `RemoteEndpoint` functionality to `Session`.
* Renamed `WebSocketPolicy` to `Configurable`.
* Renamed `WriteCallback` to just `Callback`, as it is now also used for some listener methods.
* Renamed `@OnWebSocketConnect` to `@OnWebSocketOpen`
* Renamed `Session.Listener.onWebSocketConnect()` to `onWebSocketOpen()`.
* Removed `@WebSocket` annotation attributes, because they were just a subset of the configurable ones and they can be configured directly on the Session instance.
* Removed `Session.suspend()` and `SuspendToken`, and introduced `Session.demand()`.
* Introduced `@WebSocket.autoDemand` and `Session.Listener.AutoDemanding` to support automatic demand upon exit of WebSocket handler methods.
* Removed `FrameHandler.isAutoDemanding()` and `CoreSession.isAutoDemanding()`.
* Changed the responsibility of demand from `WebSocketCoreSession` to `FrameHandler`, which in turn may delegate to `MessageSink`.
* Updated MessageInputStream to fail if an exception is thrown by the application.
Signed-off-by: Simone Bordet <simone.bordet@gmail.com>