Add standard checks to the assigning of a country name

Add check to ensure a country by that name does not exist.
Ensure the length is not too long.  Note this is a change
behaviour for edit and change commands which used to silently
truncate long names.  Enforce that a country name can not have
control characters in it.  Ensure that a country name is not
blank or just spaces.

src/lib/commands/add.c

@@ -84,12 +84,10 @@ add(void)
     }
     natp = getnatp(coun);
     p = getstarg(player->argp[2], "Country Name? ", buf);
-    if (p == 0 || *p == 0)
+    if (p ==0)
 	return RET_SYN;
-    if (strlen(p) >= sizeof(cntryname)) {
-	pr("Country name too long\n");
+    if (!check_nat_name(p))
 	return RET_FAIL;
-    }
     strcpy(cntryname, p);
     p = getstarg(player->argp[3], "Representative? ", buf);
     if (p == 0 || *p == 0)

src/lib/commands/chan.c

@@ -33,7 +33,6 @@
 
 #include <config.h>
 
-#include <ctype.h>
 #include "commands.h"
 #include "news.h"
 #include "optlist.h"
@@ -41,12 +40,8 @@
 int
 chan(void)
 {
-    char *temp;
-    struct natstr *natp;
     char *p;
-    natid cn;
     int charge;
-    int nonb;
     int btucost;
     char buf[1024];
     struct natstr *us;
@@ -84,25 +79,8 @@ chan(void)
 	if ((p =
 	     getstarg(player->argp[2], "New country name -- ", buf)) == 0)
 	    return RET_SYN;
-	p[sizeof(us->nat_cnam) - 1] = 0;
-	for (cn = 0; NULL != (natp = getnatp(cn)); cn++) {
-	    if (!strcmp(p, natp->nat_cnam)) {
-		pr("Country #%d is already called `%s'!\n", cn, p);
-		return RET_FAIL;
-	    }
-	}
-	nonb = 0;
-	for (temp = p; *temp != '\0'; temp++) {
-	    if (iscntrl(*temp)) {
-		pr("No control characters allowed in country names!\n");
-		return RET_FAIL;
-	    } else if (*temp != ' ')
-		nonb = 1;
-	}
-	if (!nonb) {
-	    pr("Must have a non-blank name!\n");
+	if (!check_nat_name(p))
 	    return RET_FAIL;
-	}
 	player->dolcost += charge;
 	player->btused += btucost;
 	strcpy(us->nat_cnam, p);

src/lib/commands/edit.c

@@ -655,8 +655,10 @@ docountry(char op, int arg, char *p, struct natstr *np)
 
     switch (op) {
     case 'n':
+	if (!check_nat_name(p))
+	    return RET_SYN;
 	pr("Country name changed from %s to %s\n", np->nat_cnam, p);
-	strncpy(np->nat_cnam, p, sizeof(np->nat_cnam) - 1);
+	strcpy(np->nat_cnam, p);
 	break;
     case 'r':
 	pr("Country representative changed from %s to %s\n",