add animation, stop automatic slideshow when interacted with

static/js/snap-gallery.js

@@ -27,6 +27,9 @@ function moveLightboxItem(id, n) {
 // Next/previous controls for slideshow
 function moveSlideshowItem(id, n) {
   showItem(slideshow_baseid, id, imageIndex[id] += n, ".snap-image");
+
+  // Kill automatic slideshow once the slideshow has been moved
+  clearInterval(autoSlideshow);
 }
 
 // In the slideshow or lightbox, make a specific image visible, make others hidden