Fixed host.os table to be a 1 based array rather than 0 based.

CHANGELOG

@@ -1,5 +1,7 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE] host.os table is now properly a 1 based array (was 0). [Patrick]
+
 o [Zenmap] Zenmap now parses and records XSL stylesheet information
   from Nmap XML files, so files saved by Zenmap will be viewable in a
   web browser just like those produced by Nmap. [David]

nse_nmaplib.cc

@@ -334,7 +334,7 @@ void set_hostinfo(lua_State *L, Target *currenths) {
     // this will run at least one time and at most 8 times, see if condition
     for(i = 0; FPR->accuracy[i] == 1; i++) {
       lua_pushstring(L, FPR->prints[i]->OS_name);
-      lua_rawseti(L, -2, i);
+      lua_rawseti(L, -2, i+1);
     }
     lua_setfield(L, -2, "os");
   }