Added RPC channel and guild entities, Get and Select methods

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

@@ -0,0 +1,34 @@
+#pragma warning disable CS1591
+using Newtonsoft.Json;
+
+namespace Discord.API.Rpc
+{
+    public class Channel
+    {
+        //Shared
+        [JsonProperty("id")]
+        public ulong Id { get; set; }
+        [JsonProperty("type")]
+        public ChannelType Type { get; set; }
+
+        //GuildChannel
+        [JsonProperty("guild_id")]
+        public Optional<ulong> GuildId { get; set; }
+        [JsonProperty("name")]
+        public Optional<string> Name { get; set; }
+        [JsonProperty("position")]
+        public Optional<int> Position { get; set; }
+
+        //IMessageChannel
+        [JsonProperty("messages")]
+        public Message[] Messages { get; set; }
+
+        //VoiceChannel
+        [JsonProperty("bitrate")]
+        public Optional<int> Bitrate { get; set; }
+        [JsonProperty("user_limit")]
+        public Optional<int> UserLimit { get; set; }
+        [JsonProperty("voice_states")]
+        public ExtendedVoiceState[] VoiceStates { get; set; }
+    }
+}