Core: define CREATURE_FAMILY_NONE to avoid magic numbers in code

src/server/scripts/Commands/cs_pet.cpp

@@ -69,10 +69,10 @@ public:
         }
 
         CreatureTemplate const* creatureTemplate = creatureTarget->GetCreatureTemplate();
-        // Creatures with family 0 crashes the server
+        // Creatures with family CREATURE_FAMILY_NONE crashes the server
         if (!creatureTemplate->family)
         {
-            handler->PSendSysMessage("This creature cannot be tamed. (family id: 0).");
+            handler->PSendSysMessage("This creature cannot be tamed. (family id: CREATURE_FAMILY_NONE).");
             handler->SetSentErrorMessage(true);
             return false;
         }