Merge branch 'feature/selectionmodel-changed-notifications' into feature/selectionmodel-reset-handling

# Conflicts:
#	tests/Avalonia.Controls.UnitTests/SelectionModelTests.cs

src/Avalonia.Controls/ISelectionModel.cs

@@ -5,10 +5,11 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 
 namespace Avalonia.Controls
 {
-    public interface ISelectionModel
+    public interface ISelectionModel : INotifyPropertyChanged
     {
         IndexPath AnchorIndex { get; set; }
         IndexPath SelectedIndex { get; set; }

src/Avalonia.Controls/SelectionModel.cs

@@ -13,7 +13,7 @@ using Avalonia.Controls.Utils;
 
 namespace Avalonia.Controls
 {
-    public class SelectionModel : ISelectionModel, INotifyPropertyChanged, IDisposable
+    public class SelectionModel : ISelectionModel, IDisposable
     {
         private readonly SelectionNode _rootNode;
         private bool _singleSelect;