Move most readline code from InteractiveShell to terminal subclass This is the first stage of my effort to use prompt_toolkit for the terminal interface. My plan is to create a new subclass of InteractiveShell which deals with the terminal using prompt_toolkit instead of readline. To facilitate this, I am first trying to separate as much of the readline code as possible out of InteractiveShell to the TerminalInteractiveShell subclass (I don't intend the new subclass to inherit from TIS). I haven't moved any of the config options relating to readline yet, because moving them will break some people's existing config files. But if we're switching to prompt_toolkit by default, readline related config is going to be broken anyway.