Edit the command with prompt_toolkit instead of readline

[jkseppan]

The readline on some Python versions is based on libedit, which doesn't support either set_startup_hook or insert_text - it just sits there waiting for input. IPython uses prompt_toolkit for editing, which feels like a more modern solution. It can even highlight the shell command using Pygment's BashLexer.

Fixes #3

[simonw]

I love the prompt toolkit fix!

I'm not sold on Pyments as a default - mainly because on my terminal it actually makes things harder to read (red on black):

So not sure it's worth the dependency weight.

Maybe there's a way to make it optional.

[simonw]

https://pypi.org/project/prompt-toolkit/ looks like a clean new dependency - BSD licensed, widely used.

Actively maintained on https://github.com/prompt-toolkit/python-prompt-toolkit for 10+ years, and good documentation: https://python-prompt-toolkit.readthedocs.io/en/stable/

Plus it doesn't pull in many other dependencies - installing in a fresh environment only pulls it plus one other:

prompt-toolkit==3.0.43
wcwidth==0.2.13

[simonw]

I'm going to land this as-is and then decide what to do with pygments.

[jkseppan]

Suggestion for pygments handling in #7