Only change karma if good player does bad stuff (or vice versa).

If a +80 karma dude kills a -40 karma monster currently he will lose
karma towards +40, with this change he'd only lose karma if he kills a
good monster.
Works the same for evil people respectively.
tabs => spaces
No karma changes from killing players.

looks a bit strange, but it's all right...
Merge pull request #43 from Koveras/karmadontgoneutral

Only change karma if good player does bad stuff (or vice versa).