Re-implement chat in content. (#198)

* OOC is a word.

* Re-implement chat in content.

Content.Shared/Chat/MsgChatMessage.cs

@@ -0,0 +1,74 @@
+using System;
+using Lidgren.Network;
+using SS14.Shared.GameObjects;
+using SS14.Shared.Interfaces.Network;
+using SS14.Shared.Network;
+using SS14.Shared.Network.Messages;
+
+namespace Content.Shared.Chat
+{
+    /// <summary>
+    ///     Sent from server to client to notify the client about a new chat message.
+    /// </summary>
+    public sealed class MsgChatMessage : NetMessage
+    {
+        #region REQUIRED
+
+        public const MsgGroups GROUP = MsgGroups.Command;
+        public const string NAME = nameof(MsgChatMessage);
+        public MsgChatMessage(INetChannel channel) : base(NAME, GROUP) { }
+
+        #endregion
+
+        /// <summary>
+        ///     The channel the message is on. This can also change whether certain params are used.
+        /// </summary>
+        public ChatChannel Channel { get; set; }
+
+        /// <summary>
+        ///     The actual message contents.
+        /// </summary>
+        public string Message { get; set; }
+
+        /// <summary>
+        ///     What to "wrap" the message contents with. Example is stuff like 'Joe says: "{0}"'
+        /// </summary>
+        public string MessageWrap { get; set; }
+
+        /// <summary>
+        ///     The sending entity.
+        ///     Only applies to <see cref="ChatChannel.Local"/> and <see cref="ChatChannel.Emotes"/>.
+        /// </summary>
+        public EntityUid SenderEntity { get; set; }
+
+        public override void ReadFromBuffer(NetIncomingMessage buffer)
+        {
+            Channel = (ChatChannel) buffer.ReadByte();
+            Message = buffer.ReadString();
+            MessageWrap = buffer.ReadString();
+
+            switch (Channel)
+            {
+                case ChatChannel.Local:
+                case ChatChannel.Emotes:
+                    SenderEntity = buffer.ReadEntityUid();
+                    break;
+            }
+        }
+
+        public override void WriteToBuffer(NetOutgoingMessage buffer)
+        {
+            buffer.Write((byte)Channel);
+            buffer.Write(Message);
+            buffer.Write(MessageWrap);
+
+            switch (Channel)
+            {
+                case ChatChannel.Local:
+                case ChatChannel.Emotes:
+                    buffer.Write(SenderEntity);
+                    break;
+            }
+        }
+    }
+}