Added Rpc message entities

src/Discord.Net.Rpc/API/Rpc/MessageEvent.cs

@@ -7,6 +7,6 @@ namespace Discord.API.Rpc
         [JsonProperty("channel_id")]
         public ulong ChannelId { get; set; }
         [JsonProperty("message")]
-        public Message Message { get; set; }
+        public RpcMessage Message { get; set; }
     }
 }

src/Discord.Net.Rpc/API/Rpc/RpcMessage.cs

@@ -0,0 +1,17 @@
+using Newtonsoft.Json;
+
+namespace Discord.API.Rpc
+{
+    public class RpcMessage : Message
+    {
+        [JsonProperty("blocked")]
+        public Optional<bool> IsBlocked { get; }
+        [JsonProperty("content_parsed")]
+        public Optional<object[]> ContentParsed { get; }
+        [JsonProperty("author_color")]
+        public Optional<string> AuthorColor { get; } //#Hex
+
+        [JsonProperty("mentions")]
+        public new Optional<ulong[]> UserMentions { get; set; }
+    }
+}