Log Message:
Update to 6.1:

This is a terse description of the new features added to readline-6.1 since
the release of readline-6.0.

1.  New Features in Readline

a.  New bindable function: menu-complete-backward.

b.  In the vi insertion keymap, C-n is now bound to menu-complete by default,
    and C-p to menu-complete-backward.

c.  When in vi command mode, repeatedly hitting ESC now does nothing, even
    when ESC introduces a bound key sequence.  This is closer to how
    historical vi behaves.

d.  New bindable function: skip-csi-sequence.  Can be used as a default to
    consume key sequences generated by keys like Home and End without having
    to bind all keys.

e.  New application-settable function: rl_filename_rewrite_hook.  Can be used
    to rewite or modify filenames read from the file system before they are
    compared to the word to be completed.

f.  New bindable variable: skip-completed-text, active when completing in the
    middle of a word.  If enabled, it means that characters in the completion
    that match characters in the remainder of the word are "skipped" rather
    than inserted into the line.

g.  The pre-readline-6.0 version of menu completion is available as
    "old-menu-complete" for users who do not like the readline-6.0 version.

h.  New bindable variable: echo-control-characters.  If enabled, and the
    tty ECHOCTL bit is set, controls the echoing of characters corresponding
    to keyboard-generated signals.

i.  New bindable variable: enable-meta-key.  Controls whether or not readline
    sends the smm/rmm sequences if the terminal indicates it has a meta key
    that enables eight-bit characters.