Various audio fixes

src/Discord.Net.Core/Audio/AudioStream.cs

@@ -11,6 +11,7 @@ namespace Discord.Audio
         public override bool CanSeek => false;
         public override bool CanWrite => false;
 
+        public virtual void WriteHeader(ushort seq, uint timestamp, bool missed) { }
         public override void Write(byte[] buffer, int offset, int count)
         {
             WriteAsync(buffer, offset, count, CancellationToken.None).GetAwaiter().GetResult();

src/Discord.Net.Core/Audio/RTPFrame.cs

@@ -5,12 +5,14 @@ namespace Discord.Audio
         public readonly ushort Sequence;
         public readonly uint Timestamp;
         public readonly byte[] Payload;
+        public readonly bool Missed;
 
-        public RTPFrame(ushort sequence, uint timestamp, byte[] payload)
+        public RTPFrame(ushort sequence, uint timestamp, byte[] payload, bool missed)
         {
             Sequence = sequence;
             Timestamp = timestamp;
             Payload = payload;
+            Missed = missed;
         }
     }
 }

src/Discord.Net.Core/Net/Udp/IUdpSocket.cs

@@ -8,6 +8,8 @@ namespace Discord.Net.Udp
     {
         event Func<byte[], int, int, Task> ReceivedDatagram;
 
+        ushort Port { get; }
+
         void SetCancelToken(CancellationToken cancelToken);
         void SetDestination(string ip, int port);