Reuse undo::Changeset to retrieve last inserted text.
Introduce Cmd::Replace(Movement, Option<String>).
Refactor Cmd::Kill handling.

Do not catch interrupted error when SIGWINCH signal is received

Ensure 0 previous rows are removed when calling refresh on a freshly
created State. Before, 0+ rows were removed on an initial State
refresh. If the prompt had a newline in it, a positive number of rows
were removed, clearing past output in stdout.

Fix #109

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).

Function key
Control + arrow keys
Shift + arrow keys
Insert key

Not tested on windows

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

But undo panic: already borrowed: BorrowMutError