Core/Groups: Move all function definition from .h to .cpp

Core/Groups: Remove Group.h dependency from any .h file

--HG--
branch : trunk

src/server/game/Battlegrounds/ArenaTeam.cpp

@@ -21,6 +21,7 @@
 
 #include "ArenaTeam.h"
 #include "World.h"
+#include "Group.h"
 
 void ArenaTeamMember::ModifyPersonalRating(Player* plr, int32 mod, uint32 slot)
 {

src/server/game/Battlegrounds/BattlegroundQueue.cpp

@@ -22,6 +22,7 @@
 #include "Chat.h"
 #include "ObjectMgr.h"
 #include "Log.h"
+#include "Group.h"
 
 /*********************************************************/
 /***            BATTLEGROUND QUEUE SYSTEM              ***/