Core/Movement: Add time synchronisation (Needs tested)

Port From (https://github.com/TrinityCore/TrinityCore/commit/c19a4db1c12b8864d6c486ee8e2f0e058fb4155a)

Source/Framework/Util/MathFunctions.cs

@@ -18,6 +18,7 @@
 using Framework.Constants;
 using Framework.GameMath;
 using System;
+using System.Collections.Generic;
 using System.Numerics;
 
 public static class MathFunctions
@@ -269,6 +270,22 @@ public static class MathFunctions
         return (ushort)((byte)l | (ushort)h << 8);
     }
 
+    public static double Variance(this IEnumerable<uint> source)
+    {
+        int n = 0;
+        double mean = 0;
+        double M2 = 0;
+
+        foreach (var x in source)
+        {
+            n = n + 1;
+            double delta = x - mean;
+            mean = mean + delta / n;
+            M2 += delta * (x - mean);
+        }
+        return M2 / (n - 1);
+    }
+
     //3d math
     public static Box toWorldSpace(Matrix4x4 rotation, Vector3 translation, Box box)
     {

Source/Framework/Util/Time.cs

@@ -82,6 +82,12 @@ public static class Time
             return newMSTime - oldMSTime;
     }
 
+    public static uint GetMSTimeDiff(uint oldMSTime, DateTime newTime)
+    {
+        uint newMSTime = (uint)(newTime - ApplicationStartTime).TotalMilliseconds;
+        return GetMSTimeDiff(oldMSTime, newMSTime);
+    }
+
     public static uint GetMSTimeDiffToNow(uint oldMSTime)
     {
         var newMSTime = GetMSTime();