Game Mechanics: fix charm

[Hasbinbad]

As I understand it, charming at high levels with high efficacy is only possible with 255 charisma. I can assure you that this emulates live quite well at least during the kunark -> pop era, as I played a raiding enchanter during that period. The fact is that nobody seriously pumped charisma back in the day, so while this is seen as non-classic, it actually is.