Micropython/upysh: Improve UX by allowing calling commands interactively;
make internal classes and functions not importable (put _ before their names).
interactively means you don't have to type tons of brackets and quotes
(something alike what you expect from a normal shell),
to figure out this behavior just type cd or mv
- cp() copies a file. If the target is a directory, the file is copied
into that directory. It uses a small buffer, so it's not fast.
- ls uses ilistdir and creates a sorted output with directories listed as
the first group.
- rm optionally deletes recursive, if the target is a directory.