[7254] Cleanups and batter checking in homebind/bgEntryPoint code.

* Load homebind data early in Player::LoadFromDB and use instead initital race points
  in cases need some safe point if current coordinate broken by some reason.
* Store BG entry point in to WorldLocation and simplify calls.
* Set bg entry point at GM teleports to battleground for correct
  auto-recall position at battleground end.

src/game/MapManager.h

@@ -94,6 +94,11 @@ class MANGOS_DLL_DECL MapManager : public MaNGOS::Singleton<MapManager, MaNGOS::
             return IsValidMAP(mapid) && MaNGOS::IsValidMapCoord(x,y,z,o);
         }
 
+        static bool IsValidMapCoord(WorldLocation const& loc)
+        {
+            return IsValidMapCoord(loc.mapid,loc.x,loc.y,loc.z,loc.o);
+        }
+
         void DoDelayedMovesAndRemoves();
 
         void LoadTransports();