Display only one parser error tab, even with multiple clicks.

Author: Hosch250

RetailCoder.VBE/UI/Command/ShowParserErrorsCommand.cs

@@ -42,9 +42,16 @@ public override void Execute(object parameter)
                 return;
             }
 
+            var oldTab = _viewModel.SelectedTab;
+            
             _viewModel.AddTab(viewModel);
             _viewModel.SelectedTab = viewModel;
 
+            if (oldTab != null)
+            {
+                oldTab.CloseCommand.Execute(null);
+            }
+
             try
             {
                 var presenter = _presenterService.Presenter(_viewModel);

RetailCoder.VBE/UI/ParserErrors/ParserErrorsPresenter.cs

@@ -6,11 +6,6 @@
 
 namespace Rubberduck.UI.ParserErrors
 {
-    public interface IParserErrorsPresenterFactory
-    {
-        IParserErrorsPresenter Create();
-    }
-
     public interface IParserErrorsPresenter
     {
         void Show();