Scripts/Icecrown Citadel: Add script for Deathbringer Saurfang (only missing alliance outro due to need of spawning and moving a transport)

Scripts/Icecrown Citadel: Corrected Lord Marrowgar, should no longer target tanks with Bone Spike Graveyard, his Coldflame should now spread properly
Core/Scripts: Moved Lady Deathwhisper Mana Barrier handler to scripts
Core/Scripts: Allow AuraScript to prevent default effects by effect index
Core/Scripts: Added Is25ManRaid() method to ScriptedAI, obviously used to check if raid is 25man
Core/Achievements: Pass m_caster to UpdateAchievementCriteria for ACHIEVEMENT_CRITERIA_TYPE_BE_SPELL_TARGET

--HG--
branch : trunk

src/server/game/AI/ScriptedAI/ScriptedCreature.h

@@ -180,6 +180,9 @@ struct ScriptedAI : public CreatureAI
     // return the dungeon or raid difficulty
     Difficulty getDifficulty() { return m_difficulty; }
 
+    // return true for 25 man or 25 man heroic mode
+    bool Is25ManRaid() { return m_difficulty & 1; }
+
     template<class T> inline
     const T& DUNGEON_MODE(const T& normal5, const T& heroic10)
     {