Core/Spells: More generic implementation of Combustion

Closes #60 & #78

sql/updates/world/2011_05_10_04_world_spell_linked_spell.sql

@@ -0,0 +1,2 @@
+DELETE FROM `spell_linked_spell` WHERE `spell_trigger` = -11129;
+INSERT INTO `spell_linked_spell` VALUES (-11129, -28682, 0, 'Combustion');

src/server/game/Entities/Player/Player.cpp

@@ -19630,6 +19630,10 @@ void Player::RemoveSpellMods(Spell * spell)
 
 void Player::DropModCharge(SpellModifier * mod, Spell * spell)
 {
+    // this mod shouldn't be removed here
+    if (mod->op == SPELLMOD_CRIT_DAMAGE_BONUS)
+        return;
+
     if (spell && mod->ownerAura && mod->charges > 0)
     {
         --mod->charges;

src/server/game/Entities/Unit/Unit.cpp

@@ -7908,17 +7908,11 @@ bool Unit::HandleAuraProc(Unit * pVictim, uint32 damage, Aura * triggeredByAura,
 
                     //last charge and crit
                     if (triggeredByAura->GetCharges() <= 1 && (procEx & PROC_EX_CRITICAL_HIT))
-                    {
-                        RemoveAurasDueToSpell(28682);       //-> remove Combustion auras
                         return true;                        // charge counting (will removed)
-                    }
 
-                    // This function can be called twice during one spell hit (Area of Effect spells)
-                    // Make sure 28682 wasn't already removed by previous call
-                    if (HasAura(28682))
-                        this->CastSpell(this, 28682, true);
+                    CastSpell(this, 28682, true);
 
-                    return false; // ordinary chrages will be removed during crit chance computations.
+                    return (procEx & PROC_EX_CRITICAL_HIT) ? true : false;
                 }
                 // Empowered Fire
                 case 31656: