fixes long standing ftpd bug where two replies would be returned
to the client if a command was flagged as accepting `ARGS' but the
parser didn't know how to cope. obvious symptom of this would be
ftp client is always one error message `behind' the server.
* consistently refer to the RFC as `RFC 959' not `RFC959' or `RFC-959',
and replace refs to RFC 765 with RFC 959.
* change order of commands in cmdtab[] to: RFC 959, BSD extras, and obsolete.
* whitespace police, deprecate register, replace malloc/strcpy with strdup
cf3263f735