Enable "Add using" context action.

src/AddIns/BackendBindings/CSharpBinding/Project/CSharpBinding.addin

@@ -210,6 +210,7 @@
 		     or you can add NR5 code action providers using <CSharpCodeActionProvider> -->
 		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.AddAnotherAccessorAction" />
 		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.AddCatchTypeAction" />
+		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.AddUsingAction" />
 		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.CheckIfParameterIsNullAction" />
 		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.ConvertAnonymousDelegateToLambdaAction" />
 		<CSharpCodeActionProvider class = "ICSharpCode.NRefactory.CSharp.Refactoring.ConvertAsToCastAction" />

src/AddIns/BackendBindings/CSharpBinding/Project/Src/Completion/ImportCompletionData.cs

@@ -16,6 +16,9 @@ using ICSharpCode.SharpDevelop.Editor.CodeCompletion;
 
 namespace CSharpBinding.Completion
 {
+	/// <summary>
+	/// Completion item that introduces a using declaration.
+	/// </summary>
 	class ImportCompletionData : EntityCompletionData
 	{
 		string insertUsing;
@@ -42,11 +45,7 @@ namespace CSharpBinding.Completion
 				SD.Log.Debug("Insert using '" + insertUsing + "'");
 				var refactoringContext = SDRefactoringContext.Create(context.Editor, CancellationToken.None);
 				using (var script = refactoringContext.StartScript()) {
-					// TODO: sort usings; insert inside namespace if other usings are there; etc.
-					var prevUsing = refactoringContext.RootNode.Children.LastOrDefault(p => p is UsingDeclaration);
-					if (prevUsing != null) {
-						script.InsertAfter(prevUsing, new UsingDeclaration(insertUsing));
-					}
+					UsingHelper.InsertUsing(refactoringContext, script, new UsingDeclaration(insertUsing));
 				}
 			}
 		}

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/Parser/Statements/TryCatchStatementTests.cs

@@ -86,7 +86,7 @@ namespace ICSharpCode.NRefactory.CSharp.Parser.Statements
 			Assert.IsFalse(c2.IsMatch(c1)); // and vice versa
 		}
 
-		[Test, Ignore("broken")]
+		[Test]
 		public void CommentBeforeTryCatchFinally()
 		{
 			var stmt = ParseUtilCSharp.ParseStatement<BlockStatement>(