API renames, change ref renderer to in renderer in IDrawable, make Layer implement IDrawable.

Source/Entities/Text2d.cs

@@ -9,7 +9,7 @@ namespace DaggerFramework
         public int FontSize { get => _fontSize; set => _fontSize = value; }
         public Color FontColor { get => _fontColor; set => _fontColor = value; }
 
-        public override void OnDraw(ref Renderer renderer)
+        public override void OnDraw(in Renderer renderer)
         {
             renderer.DrawDebugText(position, _contents, _fontSize, _fontColor);
         }