Minor script core fixes
Removed useless calls in script.c
Removed nullpo calls in script.c, scripts shouldn't crash the server
Added checks in several functions in order to prevent possible crashes
*resetstatus, *resetskill, *skillpointcount, *changesex, *successremovecards, *failedremovecards, *getequipcardid, *skilleffect, *atcommand, *cardscnt, *equip, *useatcmd
Corrected *specialeffect2 behaviour, when no player was attached and another player name was supplied it would stop script execution instead of displaying the effect