This moves in the opposite direction to 'other-window' by
default, and is consistent with its repeat map.
* lisp/window.el (other-window-backward): New function bound to
'C-x O'.
(ctl-x-map): Update definition.
* doc/emacs/windows.texi (Other Window): Update docs.
* etc/NEWS: Annouce the new command.
cd31c3cb42