Clean up collections and references properly

src/Discord.Net/Models/Channel.cs

@@ -96,7 +96,6 @@ namespace Discord
 				var server = _client.Servers[_serverId];
 				server.AddChannel(this);
 				Server = server;
-				Recipient = null;
             }
 		}
 		internal override void OnUncached()
@@ -104,13 +103,17 @@ namespace Discord
 			var server = Server;
 			if (server != null)
 				server.RemoveChannel(this);
-			Server = null;
 			
 			var recipient = Recipient;
 			if (recipient != null)
 				recipient.GlobalUser.PrivateChannel = null;
-			Recipient = recipient;
-		}
+			
+			var globalMessages = _client.Messages;
+			var messages = _messages;
+			foreach (var message in messages)
+				globalMessages.TryRemove(message.Key);
+			_messages.Clear();
+        }
 
 		internal void Update(ChannelReference model)
 		{
@@ -148,7 +151,10 @@ namespace Discord
 				{
 					var oldest = _messages.Select(x => x.Value.Id).OrderBy(x => x).FirstOrDefault();
 					if (oldest != null)
-						_client.Messages.TryRemove(oldest);
+					{
+						if (_messages.TryRemove(oldest, out message))
+							_client.Messages.TryRemove(oldest);
+					}
 				}
 				_messages.TryAdd(message.Id, message);
 			}

src/Discord.Net/Models/Invite.cs

@@ -72,12 +72,7 @@ namespace Discord
 				Channel = channel;
 			}
 		}
-		internal override void OnUncached()
-		{
-			Server = null;
-			Inviter = null;
-			Channel = null;
-		}
+		internal override void OnUncached() { }
 
 		public override string ToString() => XkcdCode ?? Id;
 		

src/Discord.Net/Models/Message.cs

@@ -167,12 +167,10 @@ namespace Discord
 			var channel = Channel;
 			if (channel != null)
 				channel.RemoveMessage(this);
-			Channel = null;
 
-			var user = User;
-			/*if (user != null)
+			/*var user = User;
+			if (user != null)
 				user.RemoveMessage(this);*/
-			User = null;
 		}
 
 		internal void Update(MessageInfo model)

src/Discord.Net/Models/Role.cs

@@ -56,7 +56,6 @@ namespace Discord
 			var server = Server;
 			if (server != null)
 				server.RemoveRole(this);
-			Server = null;
         }
 
 		internal void Update(RoleInfo model)

src/Discord.Net/Models/User.cs

@@ -82,14 +82,16 @@ namespace Discord
         }
 		internal override void OnCached()
 		{
-			var server = _client.Servers[_serverId];
-			if (server != null)
+			if (_serverId != null)
 			{
+				var server = _client.Servers[_serverId];
 				server.AddMember(this);
 				if (Id == _client.CurrentUserId)
 					server.CurrentMember = this;
 				Server = server;
 			}
+			else
+				UpdateRoles(null);
 
 			var user = _client.GlobalUsers.GetOrAdd(Id);
 			user.AddUser(this);
@@ -105,12 +107,10 @@ namespace Discord
 				if (Id == _client.CurrentUserId)
 					server.CurrentMember = null;
 			}
-			Server = null;
 
 			var globalUser = GlobalUser;
 			if (globalUser != null)
 				globalUser.RemoveUser(this);
-			GlobalUser = null;
 		}
 
 		public override string ToString() => Id;
@@ -182,7 +182,11 @@ namespace Discord
 		}
 		private void UpdateRoles(IEnumerable<Role> roles)
 		{
-			var newRoles = roles.ToDictionary(x => x.Id, x => x);
+			Dictionary<string, Role> newRoles;
+			if (roles != null)
+				newRoles = roles.ToDictionary(x => x.Id, x => x);
+			else
+				newRoles = new Dictionary<string, Role>();
 			Role everyone;
 			if (_serverId != null)
 				everyone = Server.EveryoneRole;