Add keep_to option to control where To: recipients are copied on group-reply (To: or Cc:).

author: Jan Palus

diff -urN mutt-1.5.23.orig/send.c mutt-1.5.23/send.c
--- mutt-1.5.23.orig/send.c	2014-10-12 16:55:39.680846728 +0200
+++ mutt-1.5.23/send.c	2014-10-12 16:55:52.104179682 +0200
@@ -672,7 +672,7 @@
         (!in->mail_followup_to || hmfupto != MUTT_YES))
     {
       /* if (!mutt_addr_is_user(in->to)) */
-      if (flags & SENDGROUPREPLY)
+      if ( (flags & SENDGROUPREPLY) || ! option(OPTKEEPTO) )
         rfc822_append (&out->cc, in->to, 1);
       else
         rfc822_append (&out->to, in->to, 1);
--- mutt-2.0.6/init.h.orig	2021-04-07 17:47:28.950795784 +0000
+++ mutt-2.0.6/init.h	2021-04-07 17:48:57.734130406 +0000
@@ -1874,6 +1874,12 @@
   ** from your spool mailbox to your $$mbox mailbox, or as a result of
   ** a ``$mbox-hook'' command.
   */
+  { "keep_to", DT_BOOL, R_NONE, OPTKEEPTO, 0 },
+  /*
+  ** .pp
+  ** Controls where recipients from ``To:'' list go on group-reply. If \fIset\fP
+  ** they are copied to ``To:'' otherwise to ``Cc:''.
+  */
   { "mail_check",	DT_NUM,  R_NONE, {.p=&BuffyTimeout}, {.l=5} },
   /*
   ** .pp
--- mutt-2.0.6/mutt.h.orig	2021-04-07 17:47:28.950795784 +0000
+++ mutt-2.0.6/mutt.h	2021-04-07 17:50:34.977465090 +0000
@@ -479,6 +479,7 @@
   OPTINCLUDEENCRYPTED,
   OPTINCLUDEONLYFIRST,
   OPTKEEPFLAGGED,
+  OPTKEEPTO,
   OPTMUTTLISPINLINEEVAL,
   OPTMAILCAPSANITIZE,
   OPTMAILCHECKRECENT,