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/AI/ScriptedAI/ScriptedFollowerAI.cpp

@@ -11,6 +11,7 @@ EndScriptData */
 
 #include "ScriptPCH.h"
 #include "ScriptedFollowerAI.h"
+#include "Group.h"
 
 const float MAX_PLAYER_DISTANCE = 100.0f;