lib/mp-readline: Add word-based move/delete EMACS key sequences.

This commit adds backward-word, backward-kill-word, forward-word,
forward-kill-word sequences for the REPL, with bindings to Alt+F, Alt+B,
Alt+D and Alt+Backspace respectively.  It is disabled by default and can be
enabled via MICROPY_REPL_EMACS_WORDS_MOVE.

Further enabling MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE adds extra bindings
for these new sequences: Ctrl+Right, Ctrl+Left and Ctrl+W.

The features are enabled on unix micropython-coverage and micropython-dev.

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/cmdline/repl_words_move.py.exp b/tests/cmdline/repl_words_move.py.exp
new file mode 100644
index 000000000..86f6b7788
--- /dev/null
+++ b/tests/cmdline/repl_words_move.py.exp
@@ -0,0 +1,47 @@
+MicroPython \.\+ version
+Use \.\+
+>>> # word movement
+>>> # backward-word, start in word
+>>> \.\+
+1234
+>>> # backward-word, don't start in word
+>>> \.\+
+1234
+>>> # backward-word on start of line. if cursor is moved, this will result in a SyntaxError
+>>> \.\+
+6
+>>> # forward-word, start in word
+>>> \.\+
+18
+>>> # forward-word, don't start in word
+>>> \.\+
+16
+>>> # forward-word on eol. if cursor is moved, this will result in a SyntaxError
+>>> \.\+
+6
+>>> 
+>>> # kill word
+>>> # backward-kill-word, start in word
+>>> \.\+
+123
+>>> # backward-kill-word, don't start in word
+>>> \.\+
+101
+>>> # forward-kill-word, start in word
+>>> \.\+
+123
+>>> # forward-kill-word, don't start in word
+>>> \.\+
+3
+>>> 
+>>> # extra move/kill shortcuts
+>>> # ctrl-left
+>>> \.\+
+1234
+>>> # ctrl-right
+>>> \.\+
+123
+>>> # ctrl-w
+>>> \.\+
+1
+>>>