FTPD plaintext password option

[Vadim Antonov avg@postman.ncube.com]

Few changes, to provide the same functionality
as -P in telnetd.

--vadim

cpu% pwd
/sys/src/cmd/service
cpu% diff ftp.c.old ftp.c
125a126
> int   plaintext;
169a171,173
>       case 'P':
>               plaintext = 1;
>               break;
471c475,476
<       return reply("331 encrpyt challenge, %s, as a password", ch.chal);
---
>       return reply(plaintext? "331 Your password, please?" :
>                    "331 Encrypt challenge, %s, as a password", ch.chal);
479a485,486
>       char key[DESKEYLEN];
>
485c492,497
<               return reply("531 Send user id before encrypted challenge");
---
>               return reply("531 Send user id before password");
>       if(plaintext) {
>               passtokey(key, response);
>               strcpy(response, ch.chal);
>               netcrypt(key, response);
>       }
cpu%