No American city is more hospitable to those reptilian souls who wish to shed their old skin and try a new one. New Orleans is an international capital of transformations...and Mardi Gras a time when adults become children and children become adults. In olden days the masks revealed more about the maskers than did their everyday identities. Prostitutes dressed as sailors and sailors as captains or pirates. Poor blacks masked as stock brokers or kings, and mortgage bankers became cutthroat...