remove utilityLayer ref from scene, change observable to observer

src/Rendering/babylon.utilityLayerRenderer.ts

@@ -13,8 +13,8 @@ module BABYLON {
         */
         public shouldRender:boolean = true;
 
-        private _afterRenderObservable:Nullable<Observer<Scene>>;
-        private _sceneDisposeObservable:Nullable<Observer<Scene>>;
+        private _afterRenderObserver:Nullable<Observer<Scene>>;
+        private _sceneDisposeObserver:Nullable<Observer<Scene>>;
         /**
          * Instantiates a UtilityLayerRenderer
          * @param originalScene the original scene that will be rendered on top of
@@ -28,13 +28,13 @@ module BABYLON {
             this.utilityLayerScene.clearColor = new BABYLON.Color4(0,0,0,0);
             this.utilityLayerScene.autoClear = false;
 
-            this._afterRenderObservable = this.originalScene.onAfterRenderObservable.add(()=>{
+            this._afterRenderObserver = this.originalScene.onAfterRenderObservable.add(()=>{
                 if(this.shouldRender){
                     this.render();
                 }
             });
 
-            this._sceneDisposeObservable = this.originalScene.onDisposeObservable.add(()=>{
+            this._sceneDisposeObserver = this.originalScene.onDisposeObservable.add(()=>{
                 this.dispose();
             })
         }
@@ -51,11 +51,11 @@ module BABYLON {
          * Disposes of the renderer
          */
         public dispose(){
-            if(this._afterRenderObservable){
-                this.originalScene.onAfterRenderObservable.remove(this._afterRenderObservable);
+            if(this._afterRenderObserver){
+                this.originalScene.onAfterRenderObservable.remove(this._afterRenderObserver);
             }
-            if(this._sceneDisposeObservable){
-                this.originalScene.onDisposeObservable.remove(this._sceneDisposeObservable);
+            if(this._sceneDisposeObserver){
+                this.originalScene.onDisposeObservable.remove(this._sceneDisposeObserver);
             }
             this.utilityLayerScene.dispose();
         }

src/babylon.scene.ts

@@ -1382,17 +1382,6 @@
             return this._boundingBoxRenderer;
         }
 
-        private _utilityLayerRenderer:UtilityLayerRenderer;
-        /** 
-         * Gets the UtilityLayerRenderer used to render an overlay scene layer without impacting the existing scene
-         */
-        public get utilityLayerRenderer(): UtilityLayerRenderer {
-            if(!this._utilityLayerRenderer){
-                this._utilityLayerRenderer = new UtilityLayerRenderer(this);
-            }
-            return this._utilityLayerRenderer;
-        }
-
         /** 
          * Gets the outline renderer associated with the scene
          * @returns a OutlineRenderer