Implement mu_imapio_reply_string function.

* include/mailutils/imapio.h (mu_imapio_reply_string): New proto.
* libmailutils/imapio/replstr.c: New file.
* libmailutils/imapio/Makefile.am: Add replstr.c

@@ -44,6 +44,8 @@ int mu_imapio_get_trace (mu_imapio_t io);
 
 int mu_imapio_getbuf (mu_imapio_t io, char **pptr, size_t *psize);
 
+int mu_imapio_reply_string (struct _mu_imapio *io, size_t start, char **pbuf);
+  
 #ifdef __cplusplus
 }
 #endif

@@ -23,6 +23,7 @@ libimapio_la_SOURCES = \
  literal.c\
  printf.c\
  qstring.c\
+ replstr.c\
  send.c\
  trace.c\
  words.c\

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   GNU Mailutils is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GNU Mailutils is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include <mailutils/types.h>
+#include <mailutils/imapio.h>
+#include <mailutils/errno.h>
+#include <mailutils/argcv.h>
+#include <mailutils/sys/imapio.h>
+
+/* FIXME: It would be good to have a `, size_t *psize' argument, to allow
+   for passing an already allocated buffer.  This implies similar changes
+   to mu_argcv_join. */
+int
+mu_imapio_reply_string (struct _mu_imapio *io, size_t start, char **pbuf)
+{
+  if (!io->_imap_reply_ready)
+    return MU_ERR_NOENT;
+
+  if (start >= io->_imap_ws.ws_wordc)
+    return EINVAL;
+  
+  return mu_argcv_join (io->_imap_ws.ws_wordc - start,
+			io->_imap_ws.ws_wordv + start, " ",
+			mu_argcv_escape_no,
+			pbuf);
+}