* g10.c (main): Error out if --multifile is used with the commands that

don't support it yet (--sign, --clearsign, --detach-sign, --symmetric, and
--store).

* g10.c (main): Add --multifile as an alias to turn --encrypt into
--encrypt-files (plus --verify-files, --decrypt-files).

* encode.c (use_mdc), g10.c (main): Use RFC1991 and RFC2440 directly to
check for MDC usability.  Do not set the force_mdc or disable_mdc flags
since there is no point any longer.

g10/encode.c

@@ -107,6 +107,10 @@ encode_sesskey( DEK *dek, DEK **ret_dek, byte *enckey )
 static int
 use_mdc(PK_LIST pk_list,int algo)
 {
+  /* RFC-1991 and 2440 don't have MDC */
+  if(RFC1991 || RFC2440)
+    return 0;
+
   /* --force-mdc overrides --disable-mdc */
   if(opt.force_mdc)
     return 1;