message: re-export MessageConnection so that vscode-languageserver/client is self contained
  MessageConnection is exposed through CanellationSenderStrategy
diff: import {
  ErrorCodes, ResponseError, CancellationToken, CancellationTokenSource, CancellationStrategy, CancellationReceiverStrategy, CancellationSenderStrategy,
  AbstractCancellationTokenSource, Disposable, Event, Emitter, Trace, Tracer, TraceFormat, TraceOptions, SetTraceNotification, LogTraceNotification,
  - Message, NotificationMessage, RequestMessage, MessageType as RPCMessageType,
  + Message, MessageConnection, NotificationMessage, RequestMessage, MessageType as RPCMessageType,
  RequestType, RequestType0, RequestHandler, RequestHandler0, GenericRequestHandler, StarRequestHandler, HandlerResult,
  NotificationType, NotificationType0, NotificationHandler, NotificationHandler0, GenericNotificationHandler, StarNotificationHandler,
  MessageReader, PartialMessageInfo, MessageWriter, Logger, ConnectionStrategy, ConnectionOptions,
  @@ -20,7 +20,7 @@ import {
  export {
  ErrorCodes, ResponseError, CancellationToken, CancellationTokenSource, CancellationStrategy, CancellationReceiverStrategy, CancellationSenderStrategy,
  AbstractCancellationTokenSource, Disposable, Event, Emitter, Trace, Tracer, TraceFormat, TraceOptions, SetTraceNotification, LogTraceNotification,
  - Message, NotificationMessage, RequestMessage, RPCMessageType,
  + Message, MessageConnection, NotificationMessage, RequestMessage, RPCMessageType,
  RequestType, RequestType0, RequestHandler, RequestHandler0, GenericRequestHandler, StarRequestHandler, HandlerResult,
  NotificationType, NotificationType0, NotificationHandler, NotificationHandler0, GenericNotificationHandler, StarNotificationHandler,
  MessageReader, PartialMessageInfo, MessageWriter, Logger, ConnectionStrategy, ConnectionOptions,
  