Add image preload

Jellyfin.Plugin.SkinManager/Configuration/configurationpage.html

@@ -52,7 +52,8 @@
         opt.value=element.defaultCss;
         cssOptions.appendChild(opt);
       });
-      updateSelectors()
+      updateSelectors();
+      preloadPreviews();  
     }
 
     function loadOptions(skin){
@@ -78,6 +79,18 @@
       $('#options', page).html(html).trigger('create');
     }
 
+    function preloadPreviews(){
+      data.forEach(skin => {
+        if(skin.previews != undefined){
+          skin.previews.forEach(img => {
+          var image = new Image();
+          image.src = img.url;
+        }) 
+        }
+         
+      })
+    }
+
     function loadPreviews(skin){
       if(skin.previews == undefined){
         return "";