This is a terse description of the new features added to readline-6.2 since
the release of readline-6.1.
a. The history library does not try to write the history filename in the
current directory if $HOME is unset. This closes a potential security
problem if the application does not specify a history filename.
b. New bindable variable `completion-display-width' to set the number of
columns used when displaying completions.
c. New bindable variable `completion-case-map' to cause case-insensitive
completion to treat `-' and `_' as identical.
d. There are new bindable vi-mode command names to avoid readline's case-
insensitive matching not allowing them to be bound separately.
e. New bindable variable `menu-complete-display-prefix' causes the menu
completion code to display the common prefix of the possible completions
before cycling through the list, instead of after.