[ascii] Wrap Graphics in a handle

projects/asciilib2/examples/death-trap/source/DeathTrapLogic.kiss

@@ -1,4 +1,4 @@
 (defnew [] [:Int a 5])
 
 (defmethod :Void update [:Float deltaSeconds] 0)
-(defmethod :Void draw [:Graphics graphics] 0)
+(defmethod :Void draw [:Void->Graphics graphics] 0)

projects/asciilib2/src/asciilib/Game.kiss

@@ -17,4 +17,6 @@
     (gameLogic.update deltaSeconds))
 
 (defmethod draw []
-    (graphicsBackend.draw graphics))
+    (let [&mut changedGraphics false]
+        (gameLogic.draw (lambda [] (set changedGraphics true) graphics))
+        (when changedGraphics (graphicsBackend.draw graphics))))

projects/asciilib2/src/asciilib/GameLogic.hx

@@ -2,5 +2,5 @@ package asciilib;
 
 interface GameLogic {
     public function update(deltaSeconds:Float):Void;
-    public function draw(graphics:Graphics):Void;
+    public function draw(graphicsHandle:() -> Graphics):Void;
 }