Added user state (nested menus) and sub-menu to control different potential problems and system status

IUserState.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Telegram.Bot.Args;
+
+namespace ZaoBot
+{
+	interface IUserState
+	{
+		Task<IUserState> ProcessMessage(IUserState previous, MessageEventArgs e);
+	}
+}