Generalize "animated" images to "multi-frame" images

* lisp/image.el (image-animated-types): Remove.
(image-multi-frame-p): Rename from image-animated-p, and generalize.
(image-animated-p): Make obsolete alias.
(image-animate, image-nth-frame, image-animate-timeout):
Use image-multi-frame-p.
(image-animate-timeout): If no delay, use image-default-frame-delay.

* lisp/image-mode.el (image-mode, image-toggle-animation):
Use image-multi-frame-p.
(image-mode): Adjust startup message for a multi-frame image.

* lisp/gnus/shr.el (shr-put-image): Only animate images that specify a delay.
This is consistent with the old image-animated-p behavior.

* etc/NEWS: Add placeholder for this.

Fixes: debbugs:10739

1 files changed, 2 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 62d84a0788d..2eda7a5c775 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -145,6 +145,8 @@ directory, respectively.
 `f' (`image-next-frame') and `b' (`image-previous-frame') visit the
 next or previous frame.  `F' (`image-goto-frame') shows a specific frame.
 
+*** `image-animated-p' is now `image-multi-frame-p'.
+
 ---
 *** The command `image-mode-fit-frame' deletes other windows.
 When toggling, it restores the frame's previous window configuration.