Reset ItemsPresenter on Move for now.

Need to implement this in a more efficient manner.

src/Perspex.Controls/Presenters/ItemsPresenter.cs

@@ -266,6 +266,8 @@ namespace Perspex.Controls.Presenters
 
                         break;
 
+                    case NotifyCollectionChangedAction.Move:
+                        // TODO: Implement Move in a more efficient manner.
                     case NotifyCollectionChangedAction.Reset:
                         Panel.Children.RemoveAll(generator.Clear());
                         Panel.Children.AddRange(generator.Materialize(0, Items, MemberSelector));

tests/Perspex.Controls.UnitTests/Presenters/ItemsPresenterTests.cs

@@ -115,6 +115,26 @@ namespace Perspex.Controls.UnitTests.Presenters
             Assert.Equal(new[] { "foo", "baz", "baz" }, text);
         }
 
+        [Fact]
+        public void Moving_Items_Should_Update_Containers()
+        {
+            var items = new ObservableCollection<string> { "foo", "bar", "baz" };
+            var target = new ItemsPresenter
+            {
+                Items = items,
+            };
+
+            target.ApplyTemplate();
+            items.Move(2, 1);
+
+            var text = target.Panel.Children
+                .OfType<TextBlock>()
+                .Select(x => x.Text)
+                .ToList();
+
+            Assert.Equal(new[] { "foo", "baz", "bar" }, text);
+        }
+
         [Fact]
         public void Setting_Items_To_Null_Should_Remove_Containers()
         {