Exit when Escape is pressed.

Might not do anything on web, but is handy during development.

clicky-clicker/game.gd

@@ -58,4 +58,5 @@ func _update_current_ball_count():
 
 # Called every frame. 'delta' is the elapsed time since the previous frame.
 func _process(delta):
-	pass
+	if Input.is_action_just_pressed("ui_cancel"):
+		get_tree().quit()