Fix glitches caused by addition of psec to timers.

Fix glitches caused by addition of psec to timers.

* etc/NEWS: Document timer format change.
* lisp/image.el (image-animate-timer):
* lisp/time.el (display-time-world-timer):
Use timer--function and timer--args rather than raw access to
timer vector.
* lisp/gnus/gnus-art.el (gnus-article-stop-animations):
Use timer--function rather than raw access to timer vector.