Return window in DIRECTION as seen from WINDOW.
More precisely, return the nearest window in direction DIRECTION
as seen from the position of `window-point' in window WINDOW.
DIRECTION must be one of `above', `below', `left' or `right'.
WINDOW must be a live window and defaults to the selected one.
Do not return a window whose `no-other-window' parameter is
non-nil. If the nearest window's `no-other-window' parameter is
non-nil, try to find another window in the indicated direction.
If, however, the optional argument IGNORE is non-nil, return that
window even if its `no-other-window' parameter is non-nil.
Return nil if no suitable window can be found.