Fix two bugs with the context menu:

1) Prevent it from "bouncing" which happens when we queue up a lot of
   open and close events.  Stop any running animations before starting
   new ones.  This fixes #1340.

2) Prevent a bug that's not really visible to the user where we wind
   up re-initializing a context menu over and over which results in us
   binding tons of hover events.  I don't think this causes any serious
   damage, but it's probably not good.

lib/gallery.common.js

@@ -132,22 +132,23 @@
   $.fn.gallery_context_menu = function() {
     if ($(".g-context-menu li").length) {
       var hover_target = $(this).find(".g-context-menu");
+      if (hover_target.attr("context_menu_initialized")) {
+	return;
+      }
       var list = $(hover_target).find("ul");
-      var in_progress = 0;
       hover_target.find("*").removeAttr('title');
       list.hide();
       hover_target.hover(
         function() {
-          if (in_progress == 0) {
-            list.slideDown("fast", function() { in_progress = 1; });
-            $(this).find(".g-dialog-link").gallery_dialog();
-            $(this).find(".g-ajax-link").gallery_ajax();
-          }
+          list.stop(true, true).slideDown("fast");
+          $(this).find(".g-dialog-link").gallery_dialog();
+          $(this).find(".g-ajax-link").gallery_ajax();
         },
         function() {
-          list.slideUp("slow", function() { in_progress = 0; });
+          list.stop(true, true).slideUp("slow");
         }
       );
+      hover_target.attr("context_menu_initialized", 1);
     }
   };