Core/Spells: Fixed spell effect value truncation when value is a large integer

Port From (https://github.com/TrinityCore/TrinityCore/commit/2d205506bfd3a2bb253db73b121fd147928811ba)

Source/Game/Entities/Object/WorldObject.cs

@@ -1827,7 +1827,7 @@ namespace Game.Entities
             return spellInfo.GetMinRange(!IsHostileTo(target));
         }
 
-        public float ApplyEffectModifiers(SpellInfo spellInfo, uint effIndex, float value)
+        public double ApplyEffectModifiers(SpellInfo spellInfo, uint effIndex, double value)
         {
             Player modOwner = GetSpellModOwner();
             if (modOwner != null)

Source/Game/Entities/Player/Player.Spells.cs

@@ -2765,6 +2765,16 @@ namespace Game.Entities
             basevalue = (float)(basevalue + totalflat) * totalmul;
         }
 
+        public void ApplySpellMod(SpellInfo spellInfo, SpellModOp op, ref double basevalue, Spell spell = null)
+        {
+            float totalmul = 1.0f;
+            int totalflat = 0;
+
+            GetSpellModValues(spellInfo, op, spell, basevalue, ref totalflat, ref totalmul);
+
+            basevalue = (double)(basevalue + totalflat) * totalmul;
+        }
+
         public void GetSpellModValues<T>(SpellInfo spellInfo, SpellModOp op, Spell spell, T baseValue, ref int flat, ref float pct) where T : IComparable
         {
             flat = 0;