Send chat message

Added some methods to make sending chat messages much simpler/more convenient

Example usages:

    //Sends the message "Hello user" to the other person in 1000 ms
    SendChatMessage(1000, "Hello user!");
    
    //Sends a reply-message, which is either main chat or trade chat, depending on where the last message from the user came from
    //Also uses string formatting
    SendReplyChat("Command accepted: {0}", command);

    //Send a trade-chat in 500ms, with string formatting
    SendTradeChat(500, "You're purchasing {0} keys for {1} ref", keyString, refString);