ftp: output a newline on EOF when on a tty

ftp: output a newline on EOF when on a tty

Using the 'quit' command with ftp while in interactive mode -- attached
to a tty -- ends up clearing the line for the shell to use a fresh one
for the next prompt.
Using Ctrl-D to send an EOF to the application's input while in
interactive mode currently does not clear the line in the same way.

Let's force a newline when an EOF is received from a tty so that the
program exits in a more aesthetic way.

Signed-off-by: Gabriel Filion <lelutin@gmail.com>