Rename Subscription.Closed to IsClosed

Author: JPWatson

src/Adaptive.Aeron.Tests/SubscriptionTest.cs

@@ -76,7 +76,7 @@ public void Setup()
         public void ShouldEnsureTheSubscriptionIsOpenWhenPolling()
         {
             Subscription.Dispose();
-            Assert.True(Subscription.Closed);
+            Assert.True(Subscription.IsClosed);
 
             A.CallTo(() => Conductor.ReleaseSubscription(Subscription)).MustHaveHappened();
         }

src/Adaptive.Aeron/ClientConductor.cs

@@ -478,7 +478,7 @@ internal virtual void ReleaseSubscription(Subscription subscription)
             _clientLock.Lock();
             try
             {
-                if (!subscription.Closed)
+                if (!subscription.IsClosed)
                 {
                     EnsureOpen();
                     EnsureNotReentrant();

src/Adaptive.Aeron/Subscription.cs

@@ -423,7 +423,7 @@ public void Dispose()
         /// Has this object been closed and should no longer be used?
         /// </summary>
         /// <returns> true if it has been closed otherwise false. </returns>
-        public bool Closed => _fields.isClosed;
+        public bool IsClosed => _fields.isClosed;
 
 
         /// <summary>