Core/ChatCommands: Allow to use "tele" command inside of a battleground

Allow GameMasters with ".gm on" tag to use ".tele" command inside of a battleground to tele around.

src/server/scripts/Commands/cs_tele.cpp

@@ -319,7 +319,7 @@ public:
         }
 
         MapEntry const* map = sMapStore.LookupEntry(tele->mapId);
-        if (!map || map->IsBattlegroundOrArena())
+        if (!map || (map->IsBattlegroundOrArena() && (me->GetMapId() != tele->mapId || !me->IsGameMaster())))
         {
             handler->SendSysMessage(LANG_CANNOT_TELE_TO_BG);
             handler->SetSentErrorMessage(true);