Only displayed on unix terminal.
For windows, we will have to remove ANSI escape sequence when
there is no support for ANSI colors (Windows < 10).

Completer::complete takes a mutable reference.
Editor takes a Option<Rc<RefCell<Completer>>.

Breaking change: by default, iterator does not add automatically
to history anymore.

Alternative to PR #120

Not tested on windows

Some blocks are not correctly aligned/shifted (see keymap.rs).

KillRing is bound to the LineBuffer only during Kill operations.
And the ChangeSet is unbound to the LineBuffer when undoing.

The implementation is still incomplete...

Note: a Map is used instead of a Vec because I could not make
the unbound method works with a Vec.

But undo panic: already borrowed: BorrowMutError