Fixed DateTimeUtils on .Net Standard 1.1

src/Discord.Net.Core/Utils/DateTimeUtils.cs

@@ -2,12 +2,13 @@
 
 namespace Discord
 {
+    //Source: https://github.com/dotnet/coreclr/blob/master/src/mscorlib/src/System/DateTimeOffset.cs
     internal static class DateTimeUtils
     {
 #if !NETSTANDARD1_3
-        //https://github.com/dotnet/coreclr/blob/master/src/mscorlib/src/System/DateTimeOffset.cs
-        private const long UnixEpochTicks = 621355968000000000;
-        private const long UnixEpochSeconds = 62135596800;
+        private const long UnixEpochTicks = 621_355_968_000_000_000;
+        private const long UnixEpochSeconds = 62_135_596_800;
+        private const long UnixEpochMilliseconds = 62_135_596_800_000;
 #endif
 
         public static DateTimeOffset FromSnowflake(ulong value)
@@ -29,12 +30,12 @@ namespace Discord
             return new DateTimeOffset(ticks, TimeSpan.Zero);
 #endif
         }
-        public static DateTimeOffset FromUnixMilliseconds(long seconds)
+        public static DateTimeOffset FromUnixMilliseconds(long milliseconds)
         {
 #if NETSTANDARD1_3
-            return DateTimeOffset.FromUnixTimeMilliseconds(seconds);
+            return DateTimeOffset.FromUnixTimeMilliseconds(milliseconds);
 #else
-            long ticks = seconds * TimeSpan.TicksPerMillisecond + UnixEpochTicks;
+            long ticks = milliseconds * TimeSpan.TicksPerMillisecond + UnixEpochTicks;
             return new DateTimeOffset(ticks, TimeSpan.Zero);
 #endif
         }
@@ -53,8 +54,8 @@ namespace Discord
 #if NETSTANDARD1_3
             return dto.ToUnixTimeMilliseconds();
 #else
-            long seconds = dto.UtcDateTime.Ticks / TimeSpan.TicksPerMillisecond;
-            return seconds - UnixEpochSeconds;
+            long milliseconds = dto.UtcDateTime.Ticks / TimeSpan.TicksPerMillisecond;
+            return milliseconds - UnixEpochMilliseconds;
 #endif
         }
     }