* Added Cancellation support
- Added ConnectionAbortedToken to the HubConnectionContext. This allows
arbitrary code to access a handle that represents the connection lifetime
without handling OnDisconnectedAsync on the hub itself.
- Expose Abort on HubConnectionContext to allow server side methods to
abort the connection.
- Use the Abort to stop the main loop when unexpected invocation errors happen.
- Use the connection aborted token as unsubscribe from the IObservable and to complete
the IAsyncEnumerator for streaming results.
David Fowler
BrennanConroy
Pawel Kadluczka
Mikael Mengistu