Make it possible to type into the output view

[eerohele]

I feel like there's too much friction to using Tutkain: Input and Tutkain: Prompt with nested REPLs.

It might be interesting to make it possible to type into the output view, but only in the area following the prompt (e.g. user=> ).

Could maybe add on_selection_modified in a ViewEventListener that is only applicable for Tutkain output views to allow typing only in certain areas of the output view. Or maybe extend REPL syntax to "detect" the prompt? Not sure.

Need to rethink printing the prompt, though. Maybe a separate, toggleable mode for typing into the REPL?