Add optional debug flags

[joshbuker]

Being able to see the board state itself proved very handy, but it does impact performance astronomically. Being able to toggle these debug states would be very handy.

Ideas for possible flags:

• Maximum performance (disables all progress reporting)
• Refresh interval (sets the time between progress updates)
• Board debug (prints current board state, perhaps scaled to fit console size)
• Pass starting position and board size as flags instead of hard coded params (default to 1,1 8x8)