Robert de Bath's multi-purpose patch, slightly modified.

- ^E answerback is now `PuTTY'.
 - The framework is now in place for the scrollback to reset to
   bottom on display _or_ keyboard events _or_ both. An actual
   configurable option isn't yet present, but most of the code is in
   place.
 - Try to deal with the problems where incoming data gets dropped
   after decoding but before display.
 - Scrollback behaviour has changed: instead of keying it off
   `scroll' versus `delete top line', things now go into the
   scrollback from _either_ of those but only if the primary screen
   is selected. Should fix problems with `less' and talkers.
 - must_update variable has gone because rdb correctly observed that
   it didn't seem to be doing a great deal :-)

[originally from svn r328]

ssh.c

@@ -101,6 +101,9 @@ static void c_write (char *buf, int len) {
 	if (new_head != inbuf_reap) {
 	    inbuf[inbuf_head] = *buf++;
 	    inbuf_head = new_head;
+	} else {
+            term_out();
+            if( inbuf_head == inbuf_reap ) len++; else break;
 	}
     }
 }