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

Source/ImGuiRenderLayer.cs

@@ -8,10 +8,10 @@ namespace DaggerFramework
 {
     public class ImGuiRenderLayer : Layer
     {
-        protected override void OnDraw(ref Renderer renderer)
+        protected override void OnDraw(in Renderer renderer)
         {
             Layout();
-            _controller.Draw(ref renderer);
+            _controller.Draw(in renderer);
         }
 
         protected virtual void Layout() { }
@@ -307,7 +307,7 @@ namespace DaggerFramework
             Rlgl.rlEnd();
         }
 
-        public void Draw(ref Renderer renderer)
+        public void Draw(in Renderer renderer)
         {
             ImGui.Render();
             RenderCommandLists(ImGui.GetDrawData());