Extend max language code (user 'lang' property) length from 3 to 8 chars

Ragnarok (DOCKSUD) would like to use lang_COUNTRY for their language files
as  "I use es_AR and is exactly not same to es_ES"

It's trivial to extend the length more if there's a desire to do that.
That's a nice thing about the new (in v3.20) user.tab file format.

src/sbbs3/sbbsdefs.h

@@ -517,6 +517,7 @@ typedef enum {						/* Values for xtrn_t.event				*/
 							/* String lengths								*/
 #define LEN_ALIAS		25	/* User alias									*/
 #define LEN_NAME		25	/* User name									*/
+#define LEN_LANG		8	/* Language code								*/
 #define LEN_HANDLE		8	/* User chat handle 							*/
 #define LEN_NOTE		30	/* User note									*/
 #define LEN_HOST		60	/* User hostname								*/
@@ -916,7 +917,7 @@ typedef struct {						/* Users information */
 	char	alias[LEN_ALIAS+1], 		/* Alias */
 			name[LEN_NAME+1],			/* Name - Real */
 			handle[LEN_HANDLE+1],		/* Chat handle */
-			lang[4],					/* Language code (1-3 chars or blank for default) */
+			lang[LEN_LANG+1],			/* Language code (blank for default) */
 			comp[LEN_HOST+1],			/* Hostname */
 			note[LEN_NOTE+1],			/* Public notice about this user */
 			address[LEN_ADDRESS+1], 	/* Street Address */