Core/Random: Changed random functions returning doubles to return floats

Port From (https://github.com/TrinityCore/TrinityCore/commit/9894f6b802c974bb36acd7fbb0d083455a1f0f1b)

Source/Framework/Util/CollectionExtensions.cs

@@ -158,7 +158,7 @@ namespace System.Collections.Generic
         {
             float totalWeight = sequence.Sum(weightSelector);
             // The weight we are after...
-            float itemWeightIndex = (float)RandomHelper.NextDouble() * totalWeight;
+            float itemWeightIndex = RandomHelper.NextSingle() * totalWeight;
             float currentWeightIndex = 0;
 
             foreach (var item in from weightedItem in sequence select new { Value = weightedItem, Weight = weightSelector(weightedItem) })

Source/Framework/Util/RandomHelper.cs

@@ -16,9 +16,9 @@ public class RandomHelper
     /// Returns a random number between 0.0 and 1.0.
     /// </summary>
     /// <returns></returns>
-    public static double NextDouble()
+    public static float NextSingle()
     {
-        return rand.NextDouble();
+        return rand.NextSingle();
     }
 
     /// <summary>