Mostly enable support for checking format strings with -Wformat.

Basically derived from Ratbox 3.1.

include/numeric.h

@@ -28,23 +28,18 @@
 #define INCLUDED_numeric_h
 
 #include "config.h"
-
-/*
- * form_str - return a format string for a message number
- * messages are defined below
- */
-extern const char *form_str(int);
+#include "messages.h"
 
 /*
  * Reserve numerics 000-099 for server-client connections where the client
  * is local to the server. If any server is passed a numeric in this range
  * from another server then it is remapped to 100-199. -avalon
  */
-#define RPL_WELCOME          001
-#define RPL_YOURHOST         002
-#define RPL_CREATED          003
-#define RPL_MYINFO           004
-#define RPL_ISUPPORT         005
+#define RPL_WELCOME          1
+#define RPL_YOURHOST         2
+#define RPL_CREATED          3
+#define RPL_MYINFO           4
+#define RPL_ISUPPORT         5
 
 #define RPL_SNOMASK	     8