Open Tic Tac Toe - Axis

Added background changes along with the song.

Added another shell file to the settings, for setting the background.

Bug that allowed to mark an area already marked using the keyboard has been solved.

Screen of Donate and links added.

Interface update of the credits screen.

Creation of installation package for version 2.0 compatible with Ubuntu, Mint, Debian, RedHat, OpenSuse, Slackware, Fedora, CentOS and based on these distros.

Update of the Readme and screenshots in the GitHub and website documentation.