Replaced Math.Pow with left shift operator

src/Discord.Net.Core/Entities/Permissions/ChannelPermissions.cs

@@ -143,7 +143,7 @@ namespace Discord
             var perms = new List<ChannelPermission>();
             for (byte i = 0; i < Permissions.MaxBits; i++)
             {
-                ulong flag = (ulong)Math.Pow(2, i);
+                ulong flag = ((ulong)1 << i);
                 if ((RawValue & flag) != 0)
                     perms.Add((ChannelPermission)flag);
             }

src/Discord.Net.Core/Entities/Permissions/GuildPermissions.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Diagnostics;
 
 namespace Discord
@@ -161,7 +160,7 @@ namespace Discord
             // each of the GuildPermissions increments by 2^i from 0 to MaxBits
             for (byte i = 0; i < Permissions.MaxBits; i++)
             {
-                ulong flag = (ulong)Math.Pow(2, i);
+                ulong flag = ((ulong)1 << i);
                 if ((RawValue & flag) != 0)
                     perms.Add((GuildPermission)flag);
             }

src/Discord.Net.Core/Entities/Permissions/OverwritePermissions.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Diagnostics;
 
 namespace Discord
@@ -131,7 +130,8 @@ namespace Discord
             var perms = new List<ChannelPermission>();
             for (byte i = 0; i < Permissions.MaxBits; i++)
             {
-                ulong flag = (ulong)Math.Pow(2, i);
+                // first operand must be long or ulong to shift >31 bits
+                ulong flag = ((ulong)1 << i);
                 if ((AllowValue & flag) != 0)
                     perms.Add((ChannelPermission)flag);
             }
@@ -142,7 +142,7 @@ namespace Discord
             var perms = new List<ChannelPermission>();
             for (byte i = 0; i < Permissions.MaxBits; i++)
             {
-                ulong flag = (ulong)Math.Pow(2, i);
+                ulong flag = ((ulong)1 << i);
                 if ((DenyValue & flag) != 0)
                     perms.Add((ChannelPermission)flag);
             }