Resource loading system of vio engine

The resource loading is not a simple task for a game, but in a visual novel it get s more lighter as the about of resources needed became low as well as the optimization level needed it not that much high.

But in our engine, loading resources with in the init.lua which should be the start of the story is a bad practice.
1. problem comes over the load game option
2. cannot predict the amount and make a pre-load.

Therefore the resources loading mechanism should be like this.

1. Count resources weight at the beginning.
2. Load them with a pre-loader scene before the main menu.
3. Unload them at the exit under disabled SDL Quit environment.

To achieve this, first we have to make a different script named resources.lua which will hold all the resource loading instructions.

Then before proceeding to the main menu (title page) the application will be in a new state called APP_RES_LOAD and load all the resources.