Revert "Don't subscribe to chat updates with no conversations"

This reverts commit 23f2a85301.
(Why did I add this at all, lol.)

telegram/handlers.go

@@ -156,11 +156,7 @@ func (c *Client) updateNewChat(update *client.UpdateNewChat) {
 			isChannel = typeSupergroup.IsChannel
 		}
 
-		// don't subscribe to channel posters
-		if !((isChannel && update.Chat.LastReadInboxMessageID == 0) ||
-			// don't subscribe to chats with no conversation
-			// (manual adding will trigger a subscribe anyway)
-			(update.Chat.LastReadInboxMessageID == 0 && update.Chat.LastReadOutboxMessageID == 0)) {
+		if !(isChannel && update.Chat.LastReadInboxMessageID == 0) {
 			gateway.SendPresence(
 				c.xmpp,
 				c.jid,