Implements IDLE command (rfc 2177)

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2003 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 2, 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "imap4d.h"
+
+int
+imap4d_idle (struct imap4d_command *command, char *arg)
+{
+  char *sp;
+  
+  if (util_getword (arg, &sp))
+    return util_finish (command, RESP_BAD, "Too many args");
+  
+  if (util_wait_input (0) == -1)
+    return util_finish (command, RESP_NO, "Cannot idle");
+
+  util_send ("+ idling\r\n");
+  util_flush_output ();
+
+  while (1)
+    {
+      if (util_wait_input (5))
+	{
+	  int rc;
+	  char *p;
+	  char *cmd = imap4d_readline ();
+	  
+	  p = util_getword (cmd, &sp);
+	  rc = strcasecmp (p, "done") == 0;
+
+	  free (cmd);
+	  if (rc)
+	    break;
+	}
+
+      imap4d_sync ();
+      util_flush_output ();
+    }
+
+  return util_finish (command, RESP_OK, "IDLE terminated");
+}
+