Core: Cleanup locale handling.

It also fixes the recent problem of strange strings.

--HG--
branch : trunk

src/server/game/Entities/Creature/Creature.cpp

@@ -2385,9 +2385,9 @@ TrainerSpellData const* Creature::GetTrainerSpells() const
 }
 
 // overwrite WorldObject function for proper name localization
-const char* Creature::GetNameForLocaleIdx(int32 loc_idx) const
+const char* Creature::GetNameForLocaleIdx(LocaleConstant loc_idx) const
 {
-    if (loc_idx >= 0)
+    if (loc_idx != DEFAULT_LOCALE)
     {
         uint8 uloc_idx = uint8(loc_idx);
         CreatureLocale const *cl = sObjectMgr.GetCreatureLocale(GetEntry());