Fix in EtwListener.Dispose() to return after OnComplete is called on the observer

Source/AssemblyInfo.cs

@@ -5,5 +5,5 @@ using System.Reflection;
 [assembly: AssemblyCompany("MS Open Tech")]
 [assembly: AssemblyProduct("Tx (LINQ to Logs and Traces)")]
 [assembly: AssemblyCopyright("Copyright © MS Open Tech 2012")]
-[assembly: AssemblyVersion("1.0.40311.0")]
-[assembly: AssemblyFileVersion("1.0.40311.0")]
+[assembly: AssemblyVersion("1.0.40314.0")]
+[assembly: AssemblyFileVersion("1.0.40314.0")]

Source/Tx.Windows/EtwNative/EtwListener.cs

@@ -53,6 +53,10 @@ namespace Tx.Windows
             {
                 _disposed = true;
                 EtwNativeMethods.CloseTrace(_handle);
+
+                // the above causes EtwNativeMethods.OpenTrace to return sucessfuly
+                // and the thread which invokes the callbacks to finish
+                _thread.Join();
             }
         }