Shell autocompletion

Added basic auto completion for shell that can recognize files and programs. Tapping tab key twice will print all the possibilities
Using `"^"..pattern` performs better, second match does it's work well - checks for `*.lua`. There is way to make one match, as I didn't know the `"^"`, and it's `if string.match(file, "^" .. pattern .. "(.+)[.]lua")  then`