Client UTF-8 support.

(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.

man/emp_client.6

@@ -7,6 +7,9 @@ empire \- Empire client
 .BI \-k
 ]
 [
+.BI \-u
+]
+[
 .BI \-2 " outfile"
 ]
 [
@@ -37,6 +40,12 @@ the password for your country in the game
 .BI \-k
 if someone else is connected to your country, kill their connection
 .TP
+.BI \-u
+use UTF-8 rather than ASCII character set
+.IP
+This requires server version 4.2.21 or later, and a terminal that
+understands UTF-8.
+.TP
 .BI \-2 " outfile"
 redirect output to 
 .I outfile