Add basic engine to Chess app

[iProgramMC]

Planned features:

• [X] Chess engine using the minimax algorithm and alpha-beta pruning
• [ ] Sort out some kinks causing it to show symptoms of amnesia by not taking free pieces?
• [ ] GUI to switch between human and computer players
• [ ] Option to flip the board
• [ ] Random player type chosen when starting a game with the computer (white or black)
• [ ] Difficulty setting - changes the game depth between 1-4. 1 is incredibly stupid - will leap to any chance to capture a piece regardless of consequences.