Add LICENSE.txt
Add README with basic information
Open a window and set up screen constants
Add constants for the paths of the resources
Add info about the needed resource files

The game cannot function without them so checking will be done on their
loading.
Add a class to take the responsibility of loading resources
Avoid the unreadable SCREEN_SIZE[0] by splitting the info in two constants
Add information about tiled(spritesheet) resources
Background tiles' height should be the height of the screen
Add a Tileset class to deal with the tiling of the background

This is needed because some of my background images are multiple
screens large. Whats more Gosu doesn't provide any way to cut and draw
part of an image.
Move ResourceLoader in the Resources module
Add constants for the Z ordering of the layers
Fix indentation
Rename method
Freeze constant
Add a class constantly looping a set of images to imitate motion
Make a parallax background based on the looping class
Check the parallax effect
Seems reasonable that Tileset should implement enumerable
Fix long lines