Separate interfaces for entities that the clients/server can send updates for (+ placeholder implementations)

May or may not be useful

Subsurface/Source/Networking/INetSerializable.cs

@@ -0,0 +1,26 @@
+using Lidgren.Network;
+
+namespace Barotrauma.Networking
+{
+    /// <summary>
+    /// Interface for entities that the clients can send information of to the server
+    /// </summary>
+    interface IClientSerializable
+    {
+        ushort NetStateID { get; }
+
+        void ClientWrite(NetOutgoingMessage msg);
+        void ServerRead(NetIncomingMessage msg);        
+    }
+
+    /// <summary>
+    /// Interface for entities that the server can send information of to the clients
+    /// </summary>
+    interface IServerSerializable
+    {
+        ushort NetStateID { get; }
+
+        void ServerWrite(NetOutgoingMessage msg);
+        void ClientRead(NetIncomingMessage msg);
+    }
+}