Core: Cleanup locale handling.

It also fixes the recent problem of strange strings.

--HG--
branch : trunk

src/server/game/Achievements/AchievementMgr.cpp

@@ -48,7 +48,7 @@ namespace Trinity
         public:
             AchievementChatBuilder(Player const& pl, ChatMsg msgtype, int32 textId, uint32 ach_id)
                 : i_player(pl), i_msgtype(msgtype), i_textId(textId), i_achievementId(ach_id) {}
-            void operator()(WorldPacket& data, int32 loc_idx)
+            void operator()(WorldPacket& data, LocaleConstant loc_idx)
             {
                 char const* text = sObjectMgr.GetTrinityString(i_textId,loc_idx);