Implement IconLoader. Fixes broken Images page on ControlCatalog.

src/Avalonia.Windowing/IconLoader.cs

@@ -6,8 +6,15 @@ namespace Avalonia.Windowing
 {
     public class WindowIcon : IWindowIconImpl
     {
+        private IBitmapImpl _bitmap;
+        public WindowIcon(IBitmapImpl bitmap) 
+        {
+            _bitmap = bitmap;
+        }
+
         public void Save(Stream outputStream)
         {
+            _bitmap.Save(outputStream);
         }
     }
 
@@ -19,17 +26,19 @@ namespace Avalonia.Windowing
 
         public IWindowIconImpl LoadIcon(string fileName)
         {
-            return new WindowIcon();
+            return new WindowIcon(
+                AvaloniaLocator.Current.GetService<IPlatformRenderInterface>().LoadBitmap(fileName));
         }
 
         public IWindowIconImpl LoadIcon(Stream stream)
         {
-            return new WindowIcon();
+            return new WindowIcon(
+                AvaloniaLocator.Current.GetService<IPlatformRenderInterface>().LoadBitmap(stream));
         }
 
         public IWindowIconImpl LoadIcon(IBitmapImpl bitmap)
         {
-            return new WindowIcon();
+            return new WindowIcon(bitmap);
         }
     }
 }

src/Avalonia.Windowing/PlatformSettings.cs

@@ -6,6 +6,8 @@ namespace Avalonia.Windowing
     public class PlatformSettings : IPlatformSettings
     {
         public Size DoubleClickSize => new Size(4, 4);
+
+        // TODO: This needs to be read from winit somehow
         public TimeSpan DoubleClickTime => TimeSpan.FromMilliseconds(200);
     }
 }