Core/Spells: spell effect handling improvements

* Call spell effect handlers in 4 modes:
   - SPELL_EFFECT_HANDLE_LAUNCH - called when spell is launched (cast just finished)
   - SPELL_EFFECT_HANDLE_LAUNCH_TARGET - called when spell is launched for each target in spell target map
   - SPELL_EFFECT_HANDLE_HIT - called when spell hits its destination
   - SPELL_EFFECT_HANDLE_HIT_TARGET - called when spell hits it's target from spell target map
*Correctly implement SPELL_EFFECT_TRIGGER_SPELL, SPELL_EFFECT_TRIGGER_SPELL_WITH_VALUE, SPELL_EFFECT_TRIGGER_MISSILE_SPELL_WITH_VALUE, SPELL_EFFECT_TRIGGER_MISSILE_SPELL
*Remove spell system hacks which became obsolete with this commit
Core/SpellScripts:
add OnEffectLaunch, OnEffectLaunchTarget, OnEffectHit, OnEffectHitTarget hooks for new effect handle modes and remove OnEffect hook.
A generic rule of thumb how to update your scripts (will work for nearly all cases) for spell system noobs:
if your spell script used GetHitXXXX function, you need to use OnEffectHitTarget, otherwise use
OnEffectHit

src/server/scripts/Spells/spell_quest.cpp

@@ -56,7 +56,7 @@ public:
 
     void Register()
     {
-        OnEffect += SpellEffectFn(spell_generic_quest_update_entry_SpellScript::HandleDummy, _effIndex, _spellEffect);
+        OnEffectHit += SpellEffectFn(spell_generic_quest_update_entry_SpellScript::HandleDummy, _effIndex, _spellEffect);
     }
 };
 
@@ -116,7 +116,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q5206_test_fetid_skull_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHit += SpellEffectFn(spell_q5206_test_fetid_skull_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -174,7 +174,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q6124_6129_apply_salve_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q6124_6129_apply_salve_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -275,7 +275,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q11396_11399_scourging_crystal_controller_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q11396_11399_scourging_crystal_controller_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -310,7 +310,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q11396_11399_scourging_crystal_controller_dummy_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q11396_11399_scourging_crystal_controller_dummy_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -382,7 +382,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q11587_arcane_prisoner_rescue_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q11587_arcane_prisoner_rescue_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -466,7 +466,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q11730_ultrasonic_screwdriver_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q11730_ultrasonic_screwdriver_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -517,7 +517,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q12459_seeds_of_natures_wrath_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q12459_seeds_of_natures_wrath_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -575,7 +575,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q12634_despawn_fruit_tosser_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHit += SpellEffectFn(spell_q12634_despawn_fruit_tosser_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -610,7 +610,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q12683_take_sputum_sample_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHit += SpellEffectFn(spell_q12683_take_sputum_sample_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -718,7 +718,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q12937_relief_for_the_fallen_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q12937_relief_for_the_fallen_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -765,7 +765,7 @@ class spell_q10041_q10040_who_are_they : public SpellScriptLoader
 
             void Register()
             {
-                OnEffect += SpellEffectFn(spell_q10041_q10040_who_are_they_SpellScript::HandleScript, EFFECT_0, SPELL_EFFECT_SCRIPT_EFFECT);
+                OnEffectHitTarget += SpellEffectFn(spell_q10041_q10040_who_are_they_SpellScript::HandleScript, EFFECT_0, SPELL_EFFECT_SCRIPT_EFFECT);
             }
         };
 
@@ -792,7 +792,7 @@ public:
 
         void HandleDummy(SpellEffIndex /*effIndex*/)
         {
-            if (Creature* target = GetTargetUnit()->ToCreature())
+            if (Creature* target = GetHitCreature())
             {
                 if (target->HasAura(SPELL_PERMANENT_FEIGN_DEATH))
                 {
@@ -807,7 +807,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_symbol_of_life_dummy_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_symbol_of_life_dummy_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -848,7 +848,7 @@ public:
 
         void Register()
         {
-            OnEffect += SpellEffectFn(spell_q12659_ahunaes_knife_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHitTarget += SpellEffectFn(spell_q12659_ahunaes_knife_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };
 
@@ -889,7 +889,7 @@ class spell_q9874_liquid_fire : public SpellScriptLoader
 
             void Register()
             {
-                OnEffect += SpellEffectFn(spell_q9874_liquid_fire_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+                OnEffectHitTarget += SpellEffectFn(spell_q9874_liquid_fire_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
             }
         };
 
@@ -930,7 +930,7 @@ class spell_q12805_lifeblood_dummy : public SpellScriptLoader
 
             void Register()
             {
-                OnEffect += SpellEffectFn(spell_q12805_lifeblood_dummy_SpellScript::HandleScript, EFFECT_0, SPELL_EFFECT_SCRIPT_EFFECT);
+                OnEffectHitTarget += SpellEffectFn(spell_q12805_lifeblood_dummy_SpellScript::HandleScript, EFFECT_0, SPELL_EFFECT_SCRIPT_EFFECT);
             }
         };
 
@@ -968,7 +968,7 @@ public:
 
         void Register()
         {
-        OnEffect += SpellEffectFn(spell_q13280_13283_plant_battle_standard_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
+            OnEffectHit += SpellEffectFn(spell_q13280_13283_plant_battle_standard_SpellScript::HandleDummy, EFFECT_0, SPELL_EFFECT_DUMMY);
         }
     };