Updating all method names to conform to PEP8

Also factoring out board._is_valid
Adding algorithms module with Minimax class, adjusting Computer to use it
Add arbitrary state check to board.valid_move()
Passing colors through player to algorithms
Adding Minimax methods
Adding board.get_board() method that returns untouchable copy of board
Minimax algorithm working. Fixed streak checking for board[col][row]

Replaced self.board_class with self.board
Calling board.get_board() where appropriate
Making list of dict items (Python 3 quirk?)
Streak checking needed to be switched since my board is columns of rows
Removing extraneous debug statement from board class
Searching for streaks in both positive and negative directions now
Asking for first player, adding order_players function to game