$i before $salt to keep things optional

My original version had $i after $salt and required a salt (which could have been '') in order to define $i.
I changed that offline and in the HashPass demo to accept $i before $salt. If you only want one hashing, just send a 1 or ''
Original call: hashpass($password, $salt_goes_here, 3);
Better call: hashpass($password, 3, $salt_goes_here);