[ECOS] RedBoot more telnet commands when run on default port

[Grant Edwards]

I had to had code to net_io.c to handle additional telnet
feature negotiation commands when I moved from port 9000 to
port 23.

The Linux telnet program sends a some "WILL" commands if you
start it without giving a port number on the command line. That
means that with existing code

  $ telnet redbootBoard 23   # OK
  $ telnet redbootBoard      # garbage in input buffer

I'll submit a patch later this week.

-- 
Grant Edwards
grante@visi.com