Core/Spell Mechanics: introduce global cooldown manager for server-side checks for GCD (ported from mangos)

src/server/game/Entities/Creature/Creature.h

@@ -577,7 +577,6 @@ class Creature : public Unit, public GridObject<Creature>
         uint32 m_spells[CREATURE_MAX_SPELLS];
         CreatureSpellCooldowns m_CreatureSpellCooldowns;
         CreatureSpellCooldowns m_CreatureCategoryCooldowns;
-        uint32 m_GlobalCooldown;
 
         bool canStartAttack(Unit const* u, bool force) const;
         float GetAttackDistance(Unit const* pl) const;
@@ -646,8 +645,6 @@ class Creature : public Unit, public GridObject<Creature>
         void GetHomePosition(float &x, float &y, float &z, float &ori) { m_homePosition.GetPosition(x, y, z, ori); }
         Position GetHomePosition() { return m_homePosition; }
 
-        uint32 GetGlobalCooldown() const { return m_GlobalCooldown; }
-
         uint32 GetWaypointPath(){return m_path_id;}
         void LoadPath(uint32 pathid) { m_path_id = pathid; }