Crate backgammon

This is a canonical library for playeng Backgammon. Some clarifications on how we play the game:

Players: 1) Computer, 2) Opponent Board: is numerated from 1-24 beginning on the start point of the Computer. Opponent facing, this is switched and visible from the API's perspective. The bar will be used on position 25, if necessary.

Modules

bg_match	This module implements a Backgammon match
cube	This module implements all Backgammon rules
game	This module implements a Backgammon game
player	This module implements Backgammon players