* lisp/textmodes/flyspell.el (flyspell-delay-use-timer):
New user option.
(flyspell--timer): New variable.
(flyspell-check-word-p): Use them.
(flyspell-post-command-hook): Disable timer.
(flyspell-word): Pass non-nil SECONDS argument to
'accept-process-output' to avoid blocking when called from a
timer, in which case quitting is inhibited.
* etc/NEWS: Announce new option. (bug#74437)
