Add Mystery Block to Game

[gbusto]

Add a mystery block to the game. The things that need to be done:

1. The block ALWAYS only shows a '?' regardless of what the hit count is
2. Once the hit count reaches zero, the block will not break until all the balls have returned to the origin point
3. The block will have one of 3 things happen: 1) clear the row, 2) don't add anymore blocks for 3 turns or until the user clears the entire screen (whichever comes first), and 3) cut all the block counts in half on the screen

[gbusto]

For number 3, when the block breaks it should display the item it gives the user to collect. Maybe a 4th thing could be some form of currency to collect.

[gbusto]

Last thing to do for now is to "hit" special when you get a clear row reward. Special items such as bombs and balls.