Add ERR_DISABLED (517) from ircu.

include/numeric.h

@@ -301,6 +301,8 @@ extern const char *form_str(int);
  */
 #define ERR_WRONGPONG	     513
 
+#define ERR_DISABLED         517 /* from ircu */
+
 #define ERR_HELPNOTFOUND     524
 
 #define RPL_MODLIST          702

src/messages.tab

@@ -538,7 +538,7 @@ static  const char *  replies[] = {
 /* 514 */	NULL,
 /* 515 */	NULL,
 /* 516 */	NULL,
-/* 517 */	NULL,
+/* 517 ERR_DISABLED */		"%s :This command has been administratively disabled",
 /* 518 */	NULL,
 /* 519 */	NULL,
 /* 520 */	NULL,