Class Bomb. Any Mouse implementation can drop a Bomb to hinder another Mouse
from advancing. If a Mouse comes across a Bomb that does not belong to it,
it will explode and be "respawned" at another random location. To drop a Bomb,
Mouse should return Mouse.BOMB in the move() method.
Players should be wary with the use of the Bomb because while it may hinder the
other Mouse from advancing, it may relocate the other Mouse closer to the Cheese.