Core/Spells: implement SPELLVALUE_CRIT_CHANCE

Port From (https://github.com/TrinityCore/TrinityCore/commit/13be704cb4619ef585ae0043580e2534f62e64aa)

Source/Framework/Constants/UnitConst.cs

@@ -395,6 +395,7 @@ namespace Framework.Constants
         RadiusMod,
         MaxTargets,
         AuraStack,
+        CritChance,
         DurationPct
     }
 

Source/Game/Spells/Spell.cs

@@ -6872,7 +6872,9 @@ namespace Game.Spells
                 }
             }
 
-            float critChance = m_caster.SpellCritChanceDone(this, null, m_spellSchoolMask, m_attackType);
+            float critChance = m_spellValue.CriticalChance;
+            if (critChance == 0.0f)
+                critChance = m_caster.SpellCritChanceDone(this, null, m_spellSchoolMask, m_attackType);
             targetInfo.crit = RandomHelper.randChance(unit.SpellCritChanceTaken(m_caster, this, null, m_spellSchoolMask, critChance, m_attackType));
         }
 
@@ -6965,6 +6967,9 @@ namespace Game.Spells
                 case SpellValueMod.AuraStack:
                     m_spellValue.AuraStackAmount = value;
                     break;
+                case SpellValueMod.CritChance:
+                    m_spellValue.CriticalChance = value / 100.0f; // @todo ugly /100 remove when basepoints are double
+                    break;
                 case SpellValueMod.DurationPct:
                     m_spellValue.DurationMul = (float)value / 100.0f;
                     break;
@@ -7771,6 +7776,7 @@ namespace Game.Spells
             MaxAffectedTargets = proto.MaxAffectedTargets;
             RadiusMod = 1.0f;
             AuraStackAmount = 1;
+            CriticalChance = 0.0f;
             DurationMul = 1;
         }
 
@@ -7780,6 +7786,7 @@ namespace Game.Spells
         public float RadiusMod;
         public int AuraStackAmount;
         public float DurationMul;
+        public float CriticalChance;
     }
 
     // Spell modifier (used for modify other spells)

Source/Game/Spells/SpellManager.cs

@@ -2860,7 +2860,7 @@ namespace Game.Entities
                 spellInfo._InitializeExplicitTargetMask();
             }
 
-            // addition for binary spells, ommit spells triggering other spells
+            // addition for binary spells, omit spells triggering other spells
             foreach (var spellInfo in mSpellInfoMap.Values)
             {
                 if (!spellInfo.HasAttribute(SpellCustomAttributes.BinarySpell))