I have finally implemented sprite editor. The sprite sheet can be edit inside the engine and sliced down. Currently there is only manual slicing available, but I am planning to add automatic slicing tool in the future, which will slice down the entire sprite sheet in equally regions..
This addition is improving productivity when creating game as you can do everything from within the engine. When editing the sprite sheet you can select only the sprites you want appear in your animation, They do not have to be selected in order , which can produce very interesting results. There are many more feature on my list, which I would like to add the the sprite editor, but for now the basic sprite editor will be enough. I will definitely modify it in the near future.