[crossfire] Luck penalty does not drop back to zero

[Andreas Kirschbaum]

There is a comment indicating a possible bug in common/living.c:

/* Randomly change the players luck.  Basically, we move it
 * back neutral (if greater>0, subtract, otherwise add)
 * I believe this is supposed to be > and not >= - this means
 * if your luck is -1/1, it won't get adjusted - only when your
 * luck is worse can you hope for improvment.
 * note that if we adjusted it with it is -1/1, that check above
 * for 0 luck will happen, resulting in error.
 */

I'd like to change the code so that the luck penalty for killing players
will eventually drop back to zero. Any objections here?