Set LoadedAssembly.IsAutoLoaded before adding to AssemblyList

Adding LoadedAssy to list triggers events handlers that need
IsAutoLoaded.

ILSpy/AssemblyList.cs

@@ -128,7 +128,7 @@ namespace ICSharpCode.ILSpy
 		/// Opens an assembly from disk.
 		/// Returns the existing assembly node if it is already loaded.
 		/// </summary>
-		public LoadedAssembly OpenAssembly(string file)
+		public LoadedAssembly OpenAssembly(string file, bool isAutoLoaded=false)
 		{
 			App.Current.Dispatcher.VerifyAccess();
 			
@@ -140,6 +140,7 @@ namespace ICSharpCode.ILSpy
 			}
 			
 			var newAsm = new LoadedAssembly(this, file);
+			newAsm.IsAutoLoaded = isAutoLoaded;
 			lock (assemblies) {
 				this.assemblies.Add(newAsm);
 			}

ILSpy/LoadedAssembly.cs

@@ -255,8 +255,7 @@ namespace ICSharpCode.ILSpy
 					file = Path.Combine(dir, name.Name + ".exe");
 			}
 			if (file != null) {
-				var loaded = assemblyList.OpenAssembly(file);
-				loaded.IsAutoLoaded = true;
+				var loaded = assemblyList.OpenAssembly(file, true);
 				return loaded;
 			} else {
 				return null;
@@ -278,7 +277,7 @@ namespace ICSharpCode.ILSpy
 			
 			string file = Path.Combine(Environment.SystemDirectory, "WinMetadata", name + ".winmd");
 			if (File.Exists(file)) {
-				return assemblyList.OpenAssembly(file);
+				return assemblyList.OpenAssembly(file, true);
 			} else {
 				return null;
 			}