Fix Stop() which lacked a ConfigureAwait(). (#17)

Author: jhickson

Winton.Extensions.Threading.Actor/Internal/ActorImpl.cs

@@ -7,8 +7,6 @@ namespace Winton.Extensions.Threading.Actor.Internal
 {
     internal sealed class ActorImpl : IActor
     {
-        private readonly TaskCompletionSource<object> _stoppedPromise = new TaskCompletionSource<object>();
-
         public ActorImpl(IActorTaskFactory actorTaskFactory)
         {
             Context = new ActorContext(actorTaskFactory);
@@ -26,17 +24,16 @@ public ActorStopWork StopWork
             set => Context.StopWork = value;
         }
 
-        public Task StoppedTask => _stoppedPromise.Task;
+        public Task StoppedTask => Context.StopCompletionSource.Task;
 
         public Task Start()
         {
             return Context.Start();
         }
 
-        public async Task Stop()
+        public Task Stop()
         {
-            await Context.Stop();
-            _stoppedPromise.TrySetResult(null);
+            return Context.Stop();
         }
 
         public Task Enqueue(Action action, CancellationToken cancellationToken, ActorEnqueueOptions options)