немножко раскидал функции по отдельным файлам && add helloWorld example

src/ARP_entry.c

@@ -8,7 +8,7 @@
 
 static int syscalls_gcARPEntry(lua_State* L)
 {
-	free(lua_touserdata(L, 1));
+	free(luaL_checkudata(L, 1, syscalls_ARPEntry_metatable_name));
 
 	return 0;
 }
@@ -90,8 +90,8 @@ static int syscalls_eqAPREntry(lua_State* L)
 	lua_pushboolean(
 		L,
 		syscalls_cmpAPREntry(
-			(struct ARP_entry*)lua_touserdata(L, 1),
-			(struct ARP_entry*)lua_touserdata(L, 2)
+			luaL_checkudata(L, 1, syscalls_ARPEntry_metatable_name),
+			luaL_checkudata(L, 2, syscalls_ARPEntry_metatable_name)
 		)
 	);