Flesh out the game loop

* Use a new, currently empty `Board#winner?` method as our loop
  condition
* Add `Player#insignia` so we can print the correct player insignia
  depending on who the current player is
* Print the board and a prompt for coordinates
* Switch the current player after a player finishes moving

1 files changed, 5 insertions, 0 deletions

diff --git a/board.rb b/board.rb
index 5db93fd..df66a8d 100644
--- a/board.rb
+++ b/board.rb
@@ -1,4 +1,6 @@
 class Board
+  attr_accessor :current_player
+  
   def initialize
     @board = [
       ['.', '.', '.'],
@@ -29,4 +31,7 @@ class Board
   def update_cell(row_index, column_index, value)
     @board[row_index][column_index] = value
   end
+  
+  def winner?
+  end
 end