Add tab auto-completion

[Satharus]

Tab auto completion is pretty much standard on all shells, I've been wanting to add it but anyone is welcome to try this as a Hacktoberfest 2020 contribution :D!

I am trying to keep dependencies to a minimum, so using GNU readline is not an option, sadly.

[SuchismitaDhal]

I would like to work on it! Can you assign me the issue?

[Vamsi995]

Is this issue still open?

[Satharus]

@Vamsi995 Yes

If you'd like to tackle it go ahead :D

I've added my own implementation of readline and there is a conditional for tab input from which you can call the autocomplete functions:

Chell/src/chad-readline.c

Lines 102 to 105 in 6815ed1

	else if (input == '\t')
	{
	//code for autocomplete
	}