Reversi

Output the possible moves for O on a Reversi board.

In Reversi, you can only place a tile in a free spot such that there are one or more opponents tiles between the spot and a friendly tile in at least one direction. Directions are either horizontal, vertical, or diagonal.

For example, given:

.....
.OXX!
..X..
...!.

O can only place on spots marked with !.

Assume a board size of 8x8 and a position reachable on O's turn, from the following starting position:

........
........
........
...OX...
...XO...
........
........
........

X moves first so you can assume an odd number of tiles on the board.

Your program should output the board with valid position replaced with !. Each output should be separated by a blank line.