Core: Fix many "errors"/warnings and coding style (3)

Game

Errors were found using Cppcheck, open-source static analysis tool

src/server/game/Maps/Map.cpp

@@ -2688,7 +2688,7 @@ uint32 InstanceMap::GetMaxResetDelay() const
 /* ******* Battleground Instance Maps ******* */
 
 BattlegroundMap::BattlegroundMap(uint32 id, time_t expiry, uint32 InstanceId, Map* _parent, uint8 spawnMode)
-  : Map(id, expiry, InstanceId, spawnMode, _parent)
+  : Map(id, expiry, InstanceId, spawnMode, _parent), m_bg(NULL)
 {
     //lets initialize visibility distance for BG/Arenas
     BattlegroundMap::InitVisibilityDistance();