ctrl-x shortcut is used in default keymap twice:
* as shotrcut for WordRight action (see 0908c8baea7f85aab153fbd815fda7fdfdf6bb6d);
* as prefix for extended keybindings.
To fix the second issue, shortcut for editor.ExtendedKeyMap is
unassigned now because extended shortcuts are unused in editor in
default keymap.
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
d8277f2ed9