Moved Frame models, added default providers

src/Discord.Net.WebSocket/Net/DefaultUdpSocketProvider.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace Discord.Net.Udp
+{
+    public static class DefaultUdpSocketProvider
+    {
+#if NETSTANDARD1_3
+        public static readonly UdpSocketProvider Instance = () => 
+        {
+            try
+            {
+                return new DefaultUdpSocket();
+            }
+            catch (PlatformNotSupportedException ex)
+            {
+                throw new PlatformNotSupportedException("The default UdpSocketProvider is not supported on this platform.", ex);
+            }
+        };
+#else
+        public static readonly UdpSocketProvider Instance = () => 
+        {
+            throw new PlatformNotSupportedException("The default UdpSocketProvider is not supported on this platform.\n" +
+                "You must specify a UdpSocketProvider or target a runtime supporting .NET Standard 1.3, such as .NET Framework 4.6+.");
+        };
+#endif
+    }
+}