Add auto completion system

[SadE54]

I will use the library for a specific domain language CLI, but it could be cool to add system for autocompletion !
something like the Python Prompt Toolkit (https://python-prompt-toolkit.readthedocs.io/en/master/)
Anyway thx for the lib :)

[SadE54]

And getting syntax coloring while typing the prompt string could be nice too !

[delasource]

This would be cool for a file-browser functionality

[ProphetLamb]

On that note, for the free text Input a history would be quite nice, so that we can navigate prev/next using arrow keys. Ill see if I can hack something together

[Mart-Bogdan]

Yeah, would be nice to provide callback delegate for user code to provide completions and list of options for completions.
Both ways would have it's uses.