(login): New parameter utf8. If set, request option utf-8 from
server.
(expect, recvline): Split recvline() out of expect(). Replace or
remove some unhelpful diagnostics.
(eight_bit_clean): New.
(screen): If eight_bit_clean is set, highlighting is switched with
SO/SI. Else characters with MSB set are highlighted.
(main): New option -u to request UTF-8 and set eight_bit_clean.
Get it from environment variable LOGNAME if set,
else get the user name from the system.
(main) [_DWIN32]: Add stdin redirection ability to the Win32 port.
The client reads until stdin redirection empty and then terminates.
