Core/AreaTriggers: Implementation for sever side area triggers

- Spawn GridLoader to spawn area triggers correctly now
- Removed SAI completely
- Removed remnants of smart scripts. Created different issue for it
- Calling InitDbPhaseShift and not InDbPhaseShift
- changed SpawnId to uint64 rather than uint32
- not using CellGuidSet typedef as to not include ObjectMgr.h in the header

src/server/game/Scripting/ScriptMgr.h

@@ -25,6 +25,7 @@
 class AccountMgr;
 class AreaTrigger;
 class AreaTriggerAI;
+class AreaTriggerTemplate;
 class AuctionHouseObject;
 class Aura;
 class AuraScript;
@@ -449,6 +450,7 @@ class TC_GAME_API AreaTriggerScript : public ScriptObject
 
         // Called when the area trigger is activated by a player.
         virtual bool OnTrigger(Player* /*player*/, AreaTriggerEntry const* /*trigger*/, bool /*entered*/) { return false; }
+        virtual bool OnTriggerServer(Player* /*player*/, AreaTriggerTemplate const* /*triggerTemplate*/, bool /*entered*/) { return false; }
 };
 
 class TC_GAME_API OnlyOnceAreaTriggerScript : public AreaTriggerScript