Game uses Array/index instead of Enumerable.
Game uses Array/index instead of Enumerable.

@player_enum has been removed, and a @current_player, of Integer type,
has been introduced. This is necessary because Enumerables lack the
ability to (efficiently and reasonably) seek backwards or to a given
position.

A new method, Game#set_current_player, has been introduced which takes a
Player or Integer as a parameter and sets the current player to that
parameter. Game#current_player returns @players[@current_player].
Game#next_player now increments @current_player.

Several lines have been split up for readability.

DylanFrese/TicTacChess