(longopts): New variable.
(main): Rewrote the option-parsing loop to use GNU getopt.
Help in dbck.
(give_help): New function.
(main): Call it if -h (or --help) is given.
Reset passwords in dbck.
(reset_pwd): New variable.
(main): Set it if -P (or --clear-password) is given.
(check_persons): Reset the password if the person number equals	reset_pwd.
Grant permission in dbck.
(grant_all): New variable.
(main): Set it if -G (or --grant-all) is given.
(check_persons): Give the person all privileges if the person number
	equals grant_all.