Use Abort rather than Close to avoid AlreadyClosedException.

Go through the shutdown errors list and throw the first one
with exception included (if any). This is to notify the user
that some unusual exception has actually happened, but only after
attempting to close the connection.

Author: Hubert Plociniczak

src/client/impl/ConnectionBase.cs

@@ -334,7 +334,17 @@ public IList ShutdownReport
 
         void IDisposable.Dispose()
         {
-            Close();
+            Abort();
+            if (ShutdownReport.Count > 0)
+            {
+            	foreach (ShutdownReportEntry entry in ShutdownReport)
+            	{
+            	    if (entry.Exception != null)
+            	        throw entry.Exception;
+            	}
+            	
+            	throw new OperationInterruptedException(null);
+            }
         }
 
         ///<summary>API-side invocation of connection close.</summary>